Lighter than air balloon systems and methods

ABSTRACT

Described herein are features for a high altitude lighter-than-air (LTA) system and associated methods. The LTA may include one or more super-pressure balloons (SPB). One or more of the SPB&#39;s may include one or more interior volumes. One or more of the interior volumes may be configured to receive an LTA gas therein to supplement the free lift of the LTA system. There may be an adjustable valve or vent to release the LTA gas. One or more of the interior volumes may be configured to receive ambient air to provide a variable downward force. The SPB may use a compressor to pump in ambient air. The compressor or another valve may release ambient air to decrease the downward force. A zero-pressure balloon (ZPB) may be attached with the one or more SPB&#39;s. The ZPB may supplement lift for the system.

INCORPORATION BY REFERENCE TO ANY RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

This application is a continuation of U.S. patent application Ser. No.16/414,153, entitled LIGHTER THAN AIR BALLOON SYSTEMS AND METHODS andfiled on May 16, 2019, which is a divisional of U.S. patent applicationSer. No. 16/010,991, entitled LIGHTER THAN AIR BALLOON SYSTEMS ANDMETHODS and filed Jun. 18, 2018, which is a continuation in part of U.S.patent application Ser. No. 15/863,645, entitled CONTINUOUSMULTI-CHAMBER SUPER PRESSURE BALLOON and filed Jan. 5, 2018, now issuedas U.S. Pat. No. 10,124,875 on Nov. 13, 2018, which claims the benefitof priority to U.S. provisional patent application No. 62/443,945,entitled CONTINUOUS MULTI-CHAMBER SUPER PRESSURE PUMPKIN BALLOONS andfiled Jan. 9, 2017, and to U.S. provisional patent application No.62/574,135, entitled HIGH ALTITUDE BALLOON CONTROL SYSTEMS and filedOct. 18, 2017, and U.S. patent application Ser. No. 16/010,991 claimsthe benefit of priority to U.S. provisional patent application No.62/521,988, entitled LIGHTER THAN AIR VEHICLES AND LAUNCH SYSTEMS andfiled Jun. 19, 2017, the disclosure of each of which is herebyincorporated by reference herein in its entirety for all purposes andforms a part of this specification.

BACKGROUND Field

The technology relates generally to high altitude flight, in particularto systems and methods for lighter-than-air high altitude flight.

Description of the Related Art

High altitude flight, generally above about 50,000 feet, withlighter-than-air (LTA) systems is of interest for many applications,including communications, scientific research, meteorology,reconnaissance, tourism, and others. These and other applications imposestrict requirements on the LTA system. LTA systems can include balloonsystems in which a balloon envelope includes a lighter-than-air gas(e.g., helium or hydrogen).

SUMMARY

The embodiments disclosed herein each have several aspects no single oneof which is solely responsible for the disclosure's desirableattributes. Without limiting the scope of this disclosure, its moreprominent features will now be briefly discussed. After considering thisdiscussion, and particularly after reading the section entitled“Detailed Description” one will understand how the features of theembodiments described herein provide advantages over existing approachesto high altitude LTA flight.

Described herein are features for a high altitude lighter-than-air (LTA)system and associated methods. The LTA may include one or moresuper-pressure balloons (SPB). One or more of the SPB's may include oneor more interior volumes. One or more of the interior volumes may beconfigured to receive an LTA gas therein to supplement the free lift ofthe LTA system. There may be an adjustable valve or vent to release theLTA gas. One or more of the interior volumes may be configured toreceive ambient air to provide a variable downward force. The SPB mayuse a compressor to pump in ambient air. The compressor or another valvemay release ambient air to decrease the downward force. A zero-pressureballoon (ZPB) may be attached with the one or more SPB's. The ZPB maysupplement lift for the system.

Also described herein are systems and devices for high altitude flightusing LTA systems and methods having a tandem balloon system. Azero-pressure balloon (ZPB) is attached in tandem with a variable airsuper-pressure balloon (SPB) having multiple chambers. The ZPB provideslift for the system while the SPB provides a variable amount of ballastby pumping in or expelling out ambient air. By dividing the twofunctions among the two separate balloons, each balloon and itsassociated accessories are configured for the respective balloon'sparticular function, allowing achievement of advanced performancetargets with the LTA.

The SPB may be a continuous multi-chamber SPB. “Continuous” envelope asused herein has its usual and ordinary meaning and includes withoutlimitation an envelope that extends along a length without substantialinterruption along that length. For example, the skin or envelope thatforms the multi-chamber SPB may be continuous along the axial length ofthe envelope. The gores or other sections that form the envelope mayextend through an inner opening of a fitting at a waist section of theenvelope and continue upward and downward therefrom. The gores may besingle monolithic pieces extending along the entire length, or the goresmay be assembled with smaller gore pieces to form the large gore. Theseand other embodiments as described herein are included as “continuous”envelopes. The SPB may include two, three, four or more chambers. Theremay be more than one such multi-chamber SPB. The two or more chambersmay have interior volumes that are fluidly connected. The interiorvolume may therefore be continuous from one chamber to another adjacentchamber. In some embodiments, the chambers may be fluidly separated fromeach other yet still all be formed by a continuous envelope, asdescribed. Thus many variations may be implemented. A ring fitting orother structural element may provide structural support between eachchamber. A plurality of tendons may extend upwardly and downwardly fromthe ring around respective upper and lower chambers to bias each of theSPB chambers to a pumpkin shape. A ZPB may provide lift for the systemwhile the SPB uses a compressor to provide a variable amount of ballastair by pumping in or expelling out ambient air. In some embodiments, amulti-chamber SPB may provide lifting and descending functions, forexample where the multi-chamber SPB includes a barrier defining a firstcompartment having lift gas and a second compartment having ballast air.Various advanced performance targets relating to ascent rate, descentrate, range and maximum altitude are achievable with various scaledversions of the basic design of the LTA system.

For instance, a compressor provides air to the SPB and can be configuredfor providing a sufficient rate and volume of air at particular highaltitudes in which the LTA system will be flown. Such compressor designsallow for rapid descent, as well as high pressures within the SPB whichallows for rapid venting and ascent, both of which can be performed athigh altitudes. As further example, configurations of the SPB skin andaccompanying tendons allow for a structurally efficient and stable SPB.For instance, the chambers of the SPB may be configured to assume a“pumpkin” shape during flight capable of withstanding very largeinternal pressures, while also providing stability to prevent issuessuch as deformation of the skin, including “S-clefting.” These and otherfeatures of the LTA system provide the ability to both simultaneouslyachieve high altitude (e.g. at or above about 50,000 feet) and activelycontrol altitude over a meaningful range (e.g. more than about 20,000feet).

These and other features provide an LTA platform that can be scaled andconfigured simply for various missions and flight requirements. Forinstance, the basic design of the LTA system can be configured forhigher altitude and/or heavy lift missions with a higher capacitymulti-stage compressor, larger volume and/or more chambers of the SPB,and/or larger volume ZPB. As further example, the LTA system can beconfigured for lower altitude and/or smaller payload missions with alighter weight system, for example with a single stage compressor,smaller volume and/or fewer chambers of the SPB, and/or smaller volumeZPB. These and other features of the LTA systems described herein allowfor performing advanced maneuvers at high altitude with a scalableplatform. Thus, further described herein are associated methods ofnavigation and control with these LTA systems.

In one aspect, a continuous multi-chamber super pressure balloon (SPB)is described. The continuous multi-chamber super pressure ballooncomprises a continuous envelope and a fitting. The continuous envelopeis configured to be inflated to form a plurality of two or morechambers. Each chamber comprises a maximum inflated width. Thecontinuous envelope when inflated defines a waist. The waist has aninflated waist width located between each chamber that is less than themaximum inflated width of each chamber. The fitting is configured to bepositioned around the waist.

The various aspects may have various embodiments. The plurality of twoor more chambers may comprise a plurality of gores extending along anentire length of the continuous envelope. The continuous multi-chambersuper pressure balloon may further comprise a compressor configured topump air into the continuous envelope. The continuous multi-chambersuper pressure balloon may further comprise a plurality of tendonsconfigured to bias each chamber of the plurality of two or more chambersinto a pumpkin shape when the continuous envelope is inflated. Thecontinuous multi-chamber super pressure balloon may further comprise abarrier disposed inside the continuous envelope and fluidly separating afirst fluid compartment from a second fluid compartment. The barrier mayform a closed envelope that comprises the first fluid compartment.

In some embodiments, the continuous envelope may be further configuredto be inflated to form the plurality of two or more chambers extendingalong a central axis, and the plurality of two or more chambers maycomprise a first chamber defining a first interior volume and a secondchamber defining a second interior volume. The first chamber maycomprise an upper portion and a first maximum inflated width, and thesecond chamber may comprise a lower portion and a second maximuminflated width. The inflated waist width may be less than each of thefirst and second maximum inflated widths and be located axially betweenthe first and second maximum inflated widths. The fitting may comprise aring body extending circumferentially about the central axis anddefining an opening therethrough along the axis. The fitting may beconfigured to be positioned around the waist with the continuousenvelope extending through the opening of the fitting. The continuousmulti-chamber super pressure balloon may further comprise a firstplurality of tendons and a second plurality of tendons. The firstplurality of tendons may be configured to extend from the fitting aroundthe first chamber to the upper portion of the first chamber and to biasthe first chamber into a first pumpkin shape when the continuousenvelope is inflated. The second plurality of tendons may be configuredto extend from the fitting around the second chamber to the lowerportion of the second chamber and to bias the second chamber into asecond pumpkin shape when the continuous envelope is inflated.

In some embodiments, the plurality of two or more chambers may furthercomprise a third chamber defining a third interior volume and having athird maximum inflated width and a lower portion. The inflated secondand third chambers may define a second waist having an inflated secondwaist width that is less than each of the second and third maximuminflated widths, with the second waist width located axially between thesecond and third maximum inflated widths. The continuous multi-chambersuper pressure balloon may further comprise a second fitting and a thirdplurality of tendons. The second fitting may comprise a second ring bodyextending circumferentially about the central axis and defining a secondopening therethrough along the axis, with the second fitting configuredto be positioned around the second waist with the continuous envelopeextending through the second opening of the second fitting. The thirdplurality of tendons may be configured to extend from the second fittingaround the third chamber to the lower portion of the third chamber andto bias the third chamber into a third pumpkin shape when the continuousenvelope is inflated.

In some embodiments, the continuous multi-chamber super pressure balloonmay further comprise a barrier forming a closed envelope disposed insidethe continuous envelope and fluidly separating a first fluid compartmentinside the closed envelope from a second fluid compartment outside theclosed envelope.

In another aspect, a high altitude lighter-than-air balloon system isdescribed. The high altitude lighter-than-air balloon system comprises azero-pressure balloon and any of the continuous multi-chamber superpressure balloons described herein. The zero-pressure balloon isconfigured to receive therein a lighter-than-air gas to provide anupward lifting force to the balloon system. The continuous multi-chambersuper pressure balloon is configured to couple with the zero-pressureballoon and to receive therein a variable amount of ambient air from asurrounding atmosphere to provide a variable downward force to theballoon system.

In another aspect, a continuous multi-chamber super pressure balloon isdescribed. The continuous multi-chamber super pressure balloon comprisesa continuous envelope, a circumferential constriction, and a pluralityof tendons. The continuous envelope comprises a first section, a secondsection, and a third section. The first, second and third sections areconfigured to extend axially along a central axis with the third sectionlocated between the first and second sections. The third section has asmaller maximum inflated width than each of the first and secondsections. The circumferential constriction is configured to extendaround the continuous envelope between the first and second sections.The plurality of tendons are configured to extend from thecircumferential constriction and around the continuous envelope to biasthe first and second sections into respective first and second pumpkinshapes when the continuous envelope is inflated.

The various aspects may have various embodiments. The first section andthe second section may comprise a plurality of gores extending from anupper portion of the first section to a lower portion of the secondsection. The continuous multi-chamber super pressure balloon may furthercomprise a compressor configured to pump air into the continuousenvelope. The continuous multi-chamber super pressure balloon mayfurther comprise a barrier disposed inside the continuous envelope andfluidly separating a first fluid compartment from a second fluidcompartment. The barrier may form a closed envelope that comprises thefirst fluid compartment.

In some embodiments, the continuous envelope may further comprise one ormore additional sections having a smaller maximum inflated width thansections adjacent to the one or more additional sections, and the superpressure balloon may further comprise one or more second circumferentialconstrictions with the plurality of tendons comprising a first pluralityof tendons, a second plurality of tendons, and one or more thirdplurality of tendons. The one or more second circumferentialconstrictions may each be configured to extend around the continuousenvelope at a respective one of the one or more additional sections. Thefirst plurality of tendons may be configured to extend from thecircumferential constriction around the first section to bias the firstsection into a first pumpkin shape when the continuous envelope isinflated. The second plurality of tendons may be configured to extendbetween the circumferential constriction and the second circumferentialconstriction and around the second section to bias the second sectioninto a second pumpkin shape when the continuous envelope is inflated.The one or more third plurality of tendons may each be configured toextend from a respective one of the one or more second circumferentialconstrictions around a respective one of the sections adjacent to theone or more additional sections to bias the respective one of thesections adjacent to the one or more additional sections into respectivepumpkin shapes when the continuous envelope is inflated.

In some embodiments, the continuous multi-chamber super pressure balloonmay further comprise a barrier forming a closed envelope disposed insidethe continuous envelope and fluidly separating a first fluid compartmentinside the closed envelope from a second fluid compartment outside theclosed envelope. The first section may comprise a first chamber, thesecond section may comprise a second chamber, and the third section maycomprise a waist.

In another aspect, a method of adjusting an altitude of a high altitudeballoon system comprising a continuous multi-chamber super pressureballoon (SPB) is described. The method comprises decreasing the altitudeand increasing the altitude. Decreasing the altitude comprises causingair to enter a first section of a continuous envelope of themulti-chamber SPB, and causing air to enter a second section of thecontinuous envelope, where the first and second sections each have alarger width than a third section of the continuous envelope that islocated between the first and second sections. Increasing the altitudecomprises causing air to exit the first section, and causing air to exitthe second section. In some embodiments, causing air to enter the secondsection comprises flowing air from the first section to the secondsection.

In another aspect, a multi-chamber super pressure balloon (SPB) isdescribed. The multi-chamber SPB comprises a continuous envelope, afitting, a first plurality of tendons and a second plurality of tendons.The continuous envelope is configured to be inflated to form a pluralityof chambers extending along a central axis, the plurality of chamberscomprising a first chamber defining a first interior volume and a secondchamber defining a second interior volume. The first chamber comprises atop and a first maximum inflated width, and the second chamber comprisesa bottom and a second maximum inflated width. The inflated continuousenvelope defines a waist having an inflated waist width that is lessthan each of the first and second maximum inflated widths, the waistwidth located axially between the first and second maximum inflatedwidths. The fitting comprises a ring body extending circumferentiallyabout the central axis and defines an opening therethrough along theaxis. The fitting is configured to be positioned around the waist withthe continuous envelope extending through the opening of the fitting.The first plurality of tendons is configured to extend from the fittingaround the first chamber to the top of the first chamber and to bias thefirst chamber into a first pumpkin shape when the continuous envelope isinflated. The second plurality of tendons is configured to extend fromthe fitting around the second chamber to the bottom of the secondchamber and to bias the second chamber into a second pumpkin shape whenthe continuous envelope is inflated.

The various aspects may have various embodiments. The first chamber andthe second chamber may comprise a plurality of gores extending from thetop of the first chamber to the bottom of the second chamber. Themulti-chamber super pressure balloon may further comprise a compressorconfigured to pump air into the continuous envelope. The first interiorvolume may be in fluid communication with the second interior volume.The multi-chamber super pressure balloon may further comprise a barrierdisposed inside the continuous envelope and fluidly separating a firstfluid compartment from a second fluid compartment. The barrier may forma closed envelope that comprises the first fluid compartment.

In some embodiments, the multi-chamber super pressure balloon mayfurther comprise a third chamber, a second fitting and a third pluralityof tendons. The plurality of chambers may comprise the third chamberdefining a third interior volume and having a third maximum inflatedwidth and a bottom. The inflated second and third chambers may define asecond waist having an inflated second waist width that is less thaneach of the second and third maximum inflated widths, with the secondwaist width located axially between the second and third maximuminflated widths. The second fitting may comprise a second ring bodyextending circumferentially about the central axis and defining a secondopening therethrough along the axis. The second fitting may beconfigured to be positioned around the second waist with the continuousenvelope extending through the second opening of the second fitting. Thethird plurality of tendons may be configured to extend from the secondfitting around the third chamber to the bottom of the third chamber andto bias the third chamber into a third pumpkin shape when the continuousenvelope is inflated. The multi-chamber super pressure balloon mayfurther comprise a barrier forming a closed envelope disposed inside thecontinuous envelope and fluidly separating a first fluid compartmentinside the closed envelope from a second fluid compartment outside theclosed envelope.

In another aspect, a super pressure balloon is described. Themulti-chamber super pressure balloon comprises a continuous envelope, acircumferential constriction and a plurality of tendons. The continuousenvelope comprises a first section, a second section, and a thirdsection. The first, second and third sections are configured to extendaxially along a central axis with the third section located between thefirst and second sections, the third section having a smaller maximuminflated width than each of the first and second sections. Thecircumferential constriction is configured to extend around thecontinuous envelope between the first and second sections. The pluralityof tendons is configured to extend from the circumferential constrictionand around the continuous envelope to bias the first and second sectionsinto respective first and second pumpkin shapes when the continuousenvelope is inflated.

The various aspects may have various embodiments. The first section andthe second section may comprise a plurality of gores extending from atop of the first section to a bottom of the second section. The superpressure balloon may further comprise a compressor configured to pumpair into the continuous envelope. The first section may be in fluidcommunication with the second section. The super pressure balloon mayfurther comprise a barrier disposed inside the continuous envelope andfluidly separating a first fluid compartment from a second fluidcompartment. The barrier may form a closed envelope that comprises thefirst fluid compartment.

In some embodiments, the super pressure balloon may further comprise athird section, a second circumferential constriction, and a first,second and third plurality of tendons. The continuous envelope mayfurther comprise the third section. The second circumferentialconstriction may be configured to extend around the continuous envelopebetween the second and third sections. The plurality of tendons maycomprise the first, second and third plurality of tendons. The firstplurality of tendons may be configured to extend from thecircumferential constriction around the first section to bias the firstsection into a first pumpkin shape when the continuous envelope isinflated. The second plurality of tendons may be configured to extendbetween the circumferential constriction and the second circumferentialconstriction and around the second section to bias the second sectioninto a second pumpkin shape when the continuous envelope is inflated.The third plurality of tendons may be configured to extend from thesecond circumferential constriction around the third section to bias thethird section into a third pumpkin shape when the continuous envelope isinflated. The super pressure balloon may further comprise a barrierforming a closed envelope disposed inside the continuous envelope andfluidly separating a first fluid compartment inside the closed envelopefrom a second fluid compartment outside the closed envelope. The firstsection may comprise a first chamber, the second section may comprise asecond chamber, and the third section may comprise a waist.

In another aspect, a high altitude lighter-than-air balloon system isdescribed. The high altitude lighter-than-air balloon system comprises azero-pressure balloon and a multi-chamber super pressure balloon. Thezero-pressure balloon is configured to receive therein alighter-than-air gas to provide an upward lifting force to the balloonsystem. The multi-chamber super pressure balloon is configured to couplewith the zero-pressure balloon and to receive therein a variable amountof ambient air from a surrounding atmosphere to provide a variabledownward force to the balloon system. The multi-chamber super pressureballoon comprises a continuous envelope comprising a first chamber and asecond chamber, a fitting configured to extend around the continuousenvelope between the first and second chambers, and a plurality oftendons configured to extend from the fitting and around the continuousenvelope to bias the first and second chambers into respective first andsecond pumpkin shapes when the continuous envelope is inflated.

In another aspect, a method of adjusting an altitude of a high altitudeballoon system comprising a multi-chamber super pressure balloon (SPB)is described. The method comprises decreasing the altitude andincreasing the altitude. Decreasing the altitude comprises causing airto enter a first section of a continuous envelope of the multi-chamberSPB, and causing air to enter a second section of the continuousenvelope, wherein the first and second sections each have a larger widththan a third section of the continuous envelope that is located betweenthe first and second sections. Increasing the comprises causing air toexit the first section, and causing air to exit the second section. Insome embodiments, causing air to enter the second section comprisesflowing air from the first section to the second section.

In another aspect, a method of flying a high altitude balloon system isdescribed. The method comprises causing the high altitude balloon systemto be positioned at an altitude greater than zero feet above ground. Thehigh altitude balloon system comprises a multi-chamber super pressureballoon comprising a continuous envelope, a fitting and a plurality oftendons. The continuous envelope comprises a first chamber and a secondchamber. The fitting is configured to extend around the continuousenvelope between the first and second chambers. The plurality of tendonsis configured to extend from the fitting and around the continuousenvelope to bias the first and second chambers into respective first andsecond pumpkin shapes when the continuous envelope is inflated. In someembodiments of the method, the first chamber and the second chambercomprise a plurality of gores extending from a top of the first chamberto a bottom of the second chamber. In some embodiments of the method,the high altitude balloon system further comprises a zero-pressureballoon coupled with the multi-chamber super-pressure balloon.

In another aspect, a regenerative air ballast system for lighter thanair (LTA) flight systems is described. The regenerative air ballastsystem comprises a first super pressure balloon (SPB) chamber and asecond SPB chamber fluidly connected with the first SPB chamber. Thesecond SPB chamber comprising a flexible barrier therein that separatesa first interior portion of the second SPB chamber from a secondinterior portion of the second SPB chamber. The first interior portionof the second SPB chamber is configured to receive pressurizedatmospheric air and the second interior portion of the second SPBchamber is in fluid communication with the first SPB chamber. The firstSPB chamber is configured to receive a lighter than air lift gas.

The various aspects may have various embodiments. The regenerative airballast system may further comprise a compressor in fluid connectionwith the first interior portion of the second SPB chamber and configuredto provide the pressurized atmospheric air to the first portion. Thefirst and second SBP chambers may be pumpkin balloon chambers. Theflexible barrier may be configured to move in response to receiving thepressurized atmospheric air into the first portion, thereby increasingthe volume of the first interior portion. The flexible barrier may beconfigured to expand in response to receiving the pressurizedatmospheric air into the first portion. The flexible barrier may beconfigured to expand to conform to the first interior portion of thesecond SPB chamber. The flexible barrier may be configured to expand toconform to the first interior portion of the second SPB chamber tofurther compress the lift gas in the fluidly connected first SPBchamber, thus reducing the effectiveness of the lift gas and assistingthe increase in density and thus descent of the entire vehicle. Theregenerative air ballast system may further comprise an interconnectfluidly connecting the first and second SPB chambers. The first andsecond SBP chambers may form a first continuous multi-chambered superpressure balloon. The regenerative air ballast system may furthercomprise a second continuous multi-chambered super pressure balloonencapsulating the first continuous multi-chambered super pressureballoon while maintaining fluid connection of lift gas between the firstand second SPB. The regenerative air ballast system may further comprisea third SPB chamber fluidly connected with the first SPB. Theregenerative air ballast system may further comprise coaxial gasconnections between the first and second SPB chambers and between thesecond and third SPB chambers.

In another aspect, a regenerative air ballast system for lighter thanair (LTA) flight systems is described. The regenerative air ballastsystem comprises a first super pressure balloon (SPB) chamber fluidlycoupled with a compressor, and a second SPB chamber fluidly coupled withthe compressor. Each of the first and second SPB chambers includes aflexible barrier therein separating a first interior portion from asecond interior portion, the first interior portions configured toreceive pressurized atmospheric air and the second interior portionsconfigured to receive a lighter than air lift gas.

The various aspects may have various embodiments. The regenerative airballast system may further comprise a third SPB chamber fluidly coupledto the compressor, the third SPB chamber including a flexible barriertherein separating a first interior portion from a second interiorportion, the first interior portions configured to receive pressurizedatmospheric air and the second interior portions configured to receive alighter than air lift gas. The regenerative air ballast system mayfurther comprise the compressor. The regenerative air ballast system mayfurther comprise a support structure configured to couple the compressorto each of the SPB chambers.

In another aspect, a multichambered balloon system is described. Themultichambered balloon system comprises a plurality of continuouschambers in fluid communication and configured to receive ambient air,and a lift gas bag disposed internally to the plurality of continuouschambers and configured to receive a lighter than air lift gas. Themultichambered balloon system may further comprise a compressorconfigured to pump ambient air into the plurality of continuouschambers. A number of the plurality of chambers may be two, three, four,five, six, or more.

In another aspect, a balloon system is described. The balloon systemcomprises a plurality of ballonets, each of the plurality of ballonetsfluidly connected to a single compressor.

In another aspect, a continuous multi-chamber super pressure (SP)balloon is described. The continuous multi-chamber super pressure (SP)balloon comprises a continuous envelope forming a plurality ofpumpkin-shaped tanks, the plurality of pumpkin-shaped tanks comprising afirst tank and a second tank, where the continuous envelope comprises acircumferential constriction between the first tank and the second tank.

In some embodiments, the first tank and the second tank may comprise aplurality of gores and a plurality of tendons. The circumferentialconstriction may comprise a rope ring. The rope ring may comprise anultra-high molecular weight polyethylene rope. The rope ring maycomprise a multi-turn configuration. The circumferential constrictionmay comprise a heat-sealed portion of the continuous envelope. Thecontinuous envelope may have an interior volume, the SP balloon furthercomprising a bladder separator disposed in the interior volume betweenthe first tank and the second tank. The SP balloon may further comprisea compressor configured to pump gas into the continuous envelope. Theplurality of pumpkin-shaped tanks further may comprise a third tankadjacent the second tank, and the continuous envelope may comprise asecond circumferential constriction between the second tank and thethird tank.

In another aspect, a method of constructing a multi-chamber superpressure (SP) balloon is described. The method comprises providing acontinuous envelope to be formed into a plurality of tanks, wrapping oneor more turns of rope around a portion of the continuous envelope undernominal tension to reduce slack strain, bowing out a splice link fromthe wrapped turns of rope, making a splice with an isolation tension,pulling on ends of the rope to tighten the splice to provide adouble-tensioned configuration, and sewing the splice while in thedouble-tensioned configuration

In another aspect, a lighter-than-air (LTA) high altitude balloon systemis described. The LTA system includes a zero-pressure balloon (ZPB), asuper-pressure balloon (SPB), a centrifugal compressor, an adjustablevalve, a sensor, a control system and a plurality of tendons. The ZPB isconfigured to receive therein an LTA gas to provide an upward liftingforce to the balloon system. The super-pressure balloon (SPB) has anouter skin and is configured to couple with the ZPB. The outer skindefines an interior volume configured to receive therein a variableamount of ambient air from a surrounding atmosphere to provide avariable downward force to the balloon system. The centrifugalcompressor is in fluid communication with the ambient air and with theinterior volume of the SPB. The centrifugal compressor is configured tocompress the ambient air and pump the compressed ambient air into theinterior volume of the SPB to increase the downward force to the balloonsystem. The adjustable valve is in fluid communication with the ambientair and with the interior volume of the SPB. The valve is configured tobe adjusted to release the compressed ambient air from the interiorvolume of the SPB to the surrounding atmosphere to decrease the downwardforce to the balloon system. The sensor is coupled with the balloonsystem and configured to detect an environmental attribute. The controlsystem is in communicating connection with the sensor, with thecentrifugal compressor, and with the adjustable valve. The controlsystem is configured to control the centrifugal compressor and theadjustable valve based at least on the detected environmental attributeto control the amount of compressed air inside the SPB to control analtitude of the balloon system. The plurality of tendons is coupled withthe SPB and extends along an exterior of the outer skin of the SPB. Theplurality of tendons is configured to bias the SPB into a pumpkin-likeshape at least when a first pressure inside the SPB is greater than asecond pressure of the surrounding atmosphere.

In some embodiments of the balloon system, the centrifugal compressorcomprises two or more stages. The centrifugal compressor may beconfigured to provide at least 500 liters of the ambient air per secondto the interior volume of the SPB at altitudes above 50,000 feet. Thecentrifugal compressor may be configured to provide the ambient air tothe interior volume of the SPB such that a resulting descent rate of theballoon system is at least 10,000 feet per hour at altitudes above50,000 feet. The resulting descent rate of the balloon system may be atleast 20,000 feet per hour.

In some embodiments of the balloon system, the adjustable valve isconfigured to be adjusted to release the pumped-in ambient air from theinterior volume of the SPB to the surrounding atmosphere such that aresulting ascent rate of the balloon system is at least 10,000 feet perhour at altitudes above 50,000 feet. The resulting ascent rate of theballoon system may be at least 20,000 feet per hour.

In some embodiments of the balloon system, the centrifugal compressorcomprises two or more stages and is configured to provide at least 500liters of the ambient air per second to the interior volume of the SPBsuch that a resulting descent rate of the balloon system is at least10,000 feet per hour at altitudes above 50,000 feet, and the adjustablevalve is configured to be adjusted to release the pumped-in ambient airfrom the interior volume of the SPB to the surrounding atmosphere suchthat a resulting ascent rate of the balloon system is at least 10,000feet per hour at altitudes above 50,000 feet.

In some embodiments of the high altitude balloon, the SPB comprises twoor more SPB compartments connected in series. The SPB may include two,three, four or more SPB compartments. The SPB compartments may beconnected in series and/or in parallel.

In some embodiments, the balloon system further comprises a payloadsupport, an elongated ladder assembly, and an air hose. The payloadsupport is coupled with the SPB and is configured to support a payload.The elongated ladder assembly couples the payload support with the SPBsuch that the payload support is located below the SPB when the balloonsystem is in flight. The air hose is fluidly coupled with thecentrifugal compressor, and the centrifugal compressor is mounted withthe payload support and is fluidly coupled with the interior volume ofthe SPB via the air hose. The air hose extends along and is supported atleast in part by the elongated ladder assembly.

In some embodiments, the payload support comprises a tetrahedral framecoupled with the SPB. In some embodiments, the payload support comprisesa tetrahedral frame coupled with the SPB and configured to support apayload.

In some embodiments, the balloon system further comprises a parafoilsystem coupled with the payload support and releasably coupled with theelongated ladder assembly in a stowed configuration, the parafoil systemconfigured to release from the elongated ladder assembly and to deployinto a deployed flight configuration to controllably descend with thepayload support to a landing site.

In some embodiments, the balloon system further comprises a solar arraythat includes one or more solar panels coupled with the elongated ladderassembly, wherein the elongated ladder assembly has a length based atleast in part on avoiding shading from the balloon system duringdaylight in order to provide sunlight to the one or more solar panels.

In some embodiments, the balloon system further comprises a gimbalrotatably coupling the ZPB with the SPB, the gimbal configured to rotatethe SPB relative to the ZPB, where the SPB and the solar array arerigidly coupled with the elongated ladder assembly such that rotation ofthe SPB with the gimbal rotates the elongated ladder assembly and thesolar array to a desired orientation.

In some embodiments, the balloon system further comprises one or morerelease lines and a tear line. The one or more release lines coupleupper and lower separable portions of the gimbal. The one or morerelease lines extend near a hot wire configured to be heated and therebyburn the one or more release lines. Burning the one or more releaselines separates the upper and lower portions of the gimbal. The tearline is coupled with the ZPB and with the lower portion of the gimbal.The tear line is configured to at least partially remove one or moregores of the ZPB due to separation and falling away of the lower portionof the gimbal from the ZPB.

In another aspect, a lighter-than-air (LTA) high altitude balloon systemis described. The balloon system comprises a zero-pressure balloon(ZPB), a super-pressure balloon (SPB), a multi-stage centrifugalcompressor and an adjustable valve. The ZPB is configured to receivetherein an LTA gas to provide an upward lifting force to the balloonsystem. The super-pressure balloon (SPB) is configured to couple withthe ZPB and to receive therein ambient air to provide a downward forceto the balloon system. The multi-stage centrifugal compressor isconfigured to pump the ambient air into the SPB to increase the downwardforce to the balloon system. The multi-stage centrifugal compressor isfurther configured to pump the ambient air into the SPB such that aresulting descent rate of the balloon system is at least 10,000 feet perhour at altitudes above 50,000 feet. In some embodiments, themulti-stage centrifugal compressor is thus configured for altitudesabove about 70,000 feet. The adjustable valve is configured to releasethe pumped-in ambient air from the SPB to decrease the downward force tothe balloon system. The adjustable valve is configured to release thepumped-in ambient air from the SPB such that a resulting ascent rate ofthe balloon system is at least 10,000 feet per hour at altitudes above50,000 feet. In some embodiments, the adjustable valve is thusconfigured for altitudes above about 70,000 feet. In some embodiments,the SPB is pumpkin-shaped at least when a first pressure inside the SPBis greater than a second pressure of a surrounding atmosphere

In another aspect, a method of controlling a lighter-than-air (LTA) highaltitude balloon system through a troposphere, tropopause andstratosphere is disclosed. The balloon system comprises a zero-pressureballoon (ZPB) coupled with a super-pressure balloon (SPB), a compressorfluidly coupled with the SPB and configured to pump ambient air into theSPB, and an adjustable valve fluidly coupled with the SPB and configuredto release the pumped-in ambient air from the SPB. The method comprisesdetermining a first range of latitude and longitude coordinatescorresponding to a first portion of the tropopause having a firstplurality of altitudes corresponding respectively to a first pluralityof wind directions within the tropopause. The method further comprisescontrollably releasing, with the adjustable valve, the ambient air fromthe SPB to ascend the balloon system from the determined first range oflatitude and longitude coordinates within the troposphere and throughthe tropopause to the stratosphere, where the balloon system travelsalong a first helical trajectory through the tropopause due to the firstplurality of wind directions at the first plurality of altitudes withinthe tropopause, where the balloon system ascends at a plurality ofascent rates through the tropopause, and where at least one of theplurality of ascent rates is at least 10,000 feet per hour. The methodfurther comprises determining a second range of latitude and longitudecoordinates corresponding to a second portion of the tropopause having asecond plurality of altitudes corresponding respectively to a secondplurality of wind directions within the tropopause. The method furthercomprises controllably pumping, with the compressor, the ambient airinto the SPB to descend the balloon system from the determined secondrange of latitude and longitude coordinates within the stratosphere andthrough the tropopause to the troposphere, where the balloon systemtravels along a second helical trajectory through the tropopause due tothe second plurality of wind directions at the second plurality ofaltitudes within the tropopause, where the balloon system descends at aplurality of descent rates through the tropopause, and where at leastone of the plurality of descent rates is at least 10,000 feet per hour.

In some embodiments of the method of controlling the balloon system, atleast one of the coordinates of the first range of latitude andlongitude coordinates is not within the second range of latitude andlongitude coordinates.

In some embodiments, the method further comprises traveling in agenerally horizontal first direction through the troposphere to one ofthe coordinates of the determined first range of latitude and longitudecoordinates before controllably releasing the ambient air to ascend theballoon system through the tropopause and into the stratosphere. In someembodiments, the method further comprises traveling in a generallyhorizontal second direction through the stratosphere to one of thecoordinates of the determined second range of latitude and longitudecoordinates after ascending to the stratosphere and before controllablypumping in the ambient air to descend the balloon system through thetropopause and into the troposphere. In some embodiments, the firstdirection is different from the second direction.

In some embodiments, the method further comprises maintaining theballoon system within a persistence envelope comprising portions of thetroposphere, tropopause and stratosphere. Maintaining the balloon systemwithin the persistence envelope comprises cyclically repeating thefollowing: traveling, from a starting position within the tropospherecorresponding to one of the coordinates of the second range of latitudeand longitude coordinates, along the generally horizontal firstdirection through the troposphere to a first location of the tropospherecorresponding to one of the coordinates of the first range of latitudeand longitude coordinates; ascending from the first location of thetroposphere through the tropopause along the first helical trajectory toa second location within the stratosphere; traveling along the generallyhorizontal second direction from the second location of the stratosphereto a third location of the stratosphere corresponding to one of thecoordinates of the second range of latitude and longitude coordinates;and descending from the third location of the stratosphere through thetropopause along the second helical trajectory to an ending positionwithin the troposphere corresponding to one of the coordinates of thesecond range of latitude and longitude coordinates.

In another aspect, a lighter-than-air (LTA) high altitude balloon systemcomprises a zero-pressure balloon (ZPB) and a super-pressure balloon(SPB). The ZPB is configured to receive therein a first mass of LTA gasto provide a first upward lifting force to the balloon system. The SPBis configured to couple with the ZPB. The SPB comprises an interiorvolume configured to receive therein a second mass of LTA gas to providea second upward lifting force to the balloon system. The SPB comprises afirst valve configured to be opened and closed. The first valve whenopened allows for release of at least a portion of the second mass ofLTA gas from the SPB through the first valve to a surrounding atmosphereto decrease the second upward lifting force. The first valve when closeddoes not allow for release of the second mass of LTA gas from the SPBthrough the first valve to the surrounding atmosphere. The interiorvolume of the SPB is further configured, after release of the at least aportion of the second mass of LTA gas from the SPB, to receive therein avariable amount of ambient air from the surrounding atmosphere toprovide a variable downward force to the balloon system.

Various embodiments of the various aspects may be implemented. In someembodiments, a total mass of the first and second mass of LTA gas may beconfigured to provide from about 5% free lift to about 15% free lift atlaunch. The lifting gas may be helium or hydrogen. The high altitudeballoon system may further comprise a compressor and a fill tube fluidlyconnecting the compressor to the interior volume of the SPB, with thefill tube configured to receive the second mass of LTA gas and to allowthe second mass of LTA gas to flow through the fill tube to the interiorvolume of the SPB. The compressor may be configured to provide thevariable amount of ambient air from the surrounding atmosphere to theinterior volume of the SPB. The high altitude balloon system may furthercomprise an LTA gas inlet fluidly connected with the fill tube along aninlet flow path and a one-way valve located within the inlet flow path,with the LTA gas inlet configured to receive the second mass of LTA gasand to allow the second mass of LTA gas to flow along the inlet flowpath to the fill tube, and the one-way valve located within the inletflow path and configured to prevent backflow of the LTA gas across thevalve. After the interior volume of the SPB receives therein thevariable amount of ambient air from the surrounding atmosphere, thefirst valve when opened may allow for release of at least some of theambient air to the surrounding atmosphere to decrease the downwardforce. The high altitude balloon system may further comprise a secondvalve in fluid communication with the ambient air and with the interiorvolume of the SPB, with the second valve configured to be adjusted,after the interior volume of the SPB receives therein the variableamount of ambient air from the surrounding atmosphere, to release theambient air from the interior volume of the SPB to the surroundingatmosphere to decrease the downward force.

In some embodiments of the high altitude balloon system, the SPB maycomprise an upper chamber and a lower chamber fluidly connected with theupper chamber, where the first valve is located on the upper chamber.The high altitude balloon system may further comprise a compressor and afill tube fluidly connecting the compressor to the interior volume ofthe SPB via a connection on the lower chamber, with the fill tubeconfigured to receive the second mass of LTA gas and to allow the secondmass of LTA gas to flow through the fill tube to the interior volume ofthe SPB via the connection on the lower chamber. The compressor may beconfigured to provide the variable amount of ambient air from thesurrounding atmosphere to the interior volume of the SPB.

In another aspect, a lighter-than-air (LTA) high altitude balloon systemcomprises a zero-pressure balloon (ZPB) configured to receive therein afirst LTA gas, a super-pressure balloon (SPB) configured to couple withthe ZPB with the SPB configured to receive therein a second LTA gas, anda first valve configured to be adjusted to control release of at least aportion of the second LTA gas from the SPB. The SPB is furtherconfigured, after release of the at least a portion of the second LTAgas from the SPB, to receive therein a variable amount of ambient airfrom the surrounding atmosphere.

In some embodiments, the high altitude balloon system may furthercomprise a compressor and a fill tube fluidly connecting the compressorto the SPB, the fill tube configured to provide the second LTA gas tothe SPB. The compressor may be configured to provide the variable amountof ambient air from the surrounding atmosphere to the SPB.

In another aspect, a method of controlling buoyancy of a high altitudeballoon system comprising a super pressure balloon (SPB) is described.The method comprises releasing, while the high altitude balloon systemis in flight, an LTA gas from an interior volume of the SPB to asurrounding atmosphere and receiving, while the high altitude balloonsystem is in flight, ambient air from the surrounding atmosphere intothe interior volume of the SPB. The method may further comprisereceiving, prior to the high altitude balloon system being in flight,the LTA gas into the interior volume of the SPB. The method may furthercomprise releasing at least a portion of the ambient air from theinterior volume of the SPB to the surrounding atmosphere. The method mayfurther comprise, prior to releasing the LTA gas from the interiorvolume of the SPB, ascending the high altitude balloon system to a firstaltitude. The method may further comprise releasing the LTA gas from theinterior volume of the SPB by adjusting a valve. The method may includethe high altitude balloon system comprising a zero pressure balloon(ZPB), where the method further comprises receiving a second LTA gasinto an interior volume of the ZPB.

In another aspect, lighter-than-air (LTA) high altitude balloon systemis described. The LTA high altitude balloon system comprises azero-pressure balloon (ZPB), a super-pressure balloon (SPB), and a firstadjustable valve. The ZPB is configured to receive therein a first massof LTA gas to provide a first upward lifting force to the balloonsystem. The SPB is configured to couple with the ZPB. The SPB comprisesa first interior volume and a second interior volume, with the firstinterior volume configured to receive therein a second mass of LTA gasto provide a second upward lifting force to the balloon system, and thesecond interior volume configured to receive therein a variable amountof ambient air from a surrounding atmosphere to provide a variabledownward force to the balloon system. The first adjustable valve is influid communication with the ambient air and with the first interiorvolume of the SPB, with the first adjustable valve configured to beadjusted to release at least a portion of the second mass of LTA gasfrom the first interior volume of the SPB to the surrounding atmosphereto decrease the second upward lifting force.

Various embodiments of the various aspects may be implemented. In someembodiments, a total mass of the first and second mass of LTA gas may beconfigured to provide from about 5% free lift to about 15% free lift atlaunch. A total mass of the first and second mass of LTA gas may beconfigured to provide about 10% free lift at launch. A total mass of thefirst and second mass of lift gas may be configured to provide fromabout 5% free lift to about 15% free lift at the tropopause. The liftinggas may be helium or hydrogen. The SPB may further comprise a barrierfluidly separating the first interior volume from the second interiorvolume. The high altitude balloon system may further comprise a controlsystem configured to control the first adjustable valve to control theamount of LTA gas inside the first interior volume of the SPB to controlan altitude of the balloon system. The high altitude balloon system mayfurther comprise a second adjustable valve in fluid communication withthe ambient air and with the second interior volume of the SPB, with thesecond adjustable valve configured to be adjusted to release thecompressed ambient air from the second interior volume of the SPB to thesurrounding atmosphere to decrease the downward force. The high altitudeballoon system may further comprise a centrifugal compressor in fluidcommunication with the ambient air and with the second interior volumeof the SPB, with the centrifugal compressor configured to compress theambient air and pump the compressed ambient air into the second interiorvolume of the SPB to increase the downward force.

In another aspect, a lighter-than-air (LTA) high altitude balloon systemis described. The LTA high altitude balloon system comprises a firstsuper-pressure balloon (SPB) and a second SPB. The first SPB comprises afirst interior volume and a first adjustable valve, with the firstinterior volume configured to receive therein a first mass of LTA gas toprovide a first upward lifting force to the balloon system. The firstadjustable valve is configured to be adjusted to release at least aportion of the first mass of LTA gas from the first interior volume ofthe SPB to the surrounding atmosphere to decrease the first upwardlifting force. The second SPB comprises a second interior volume and asecond adjustable valve. The second interior volume is configured toreceive therein a variable amount of ambient air from the surroundingatmosphere to provide a variable downward force to the balloon system.The second adjustable valve is in fluid communication with the ambientair and with the second interior volume of the SPB, with the secondadjustable valve configured to be adjusted to release the ambient airfrom the second interior volume of the SPB to the surrounding atmosphereto decrease the downward force

Various embodiments of the various aspects may be implemented. In someembodiments, the first SPB may further comprise a third interior volumefluidly separated from the first interior volume, where the thirdinterior volume of the first SPB is in fluid communication with thesecond interior volume of the second SPB. The third interior volume maybe fluidly separated from the first interior volume by a barrier locatedwithin the first SPB. The high altitude balloon system may furthercomprise a zero-pressure balloon (ZPB) configured to receive therein asecond mass of LTA gas to provide a second upward lifting force to theballoon system.

In another aspect, a super-pressure balloon (SPB) is described. The SPBcomprises a first interior volume, a second interior volume and a firstadjustable valve. The first interior volume is configured to receivetherein a first mass of LTA gas to provide a first upward lifting forceto the SPB. The second interior volume is configured to receive thereina variable amount of ambient air from a surrounding atmosphere toprovide a variable downward force to the balloon system. The firstadjustable valve is in fluid communication with the ambient air and withthe first interior volume of the SPB, with the first adjustable valveconfigured to be adjusted to release at least a portion of the firstmass of LTA gas from the first interior volume of the SPB to thesurrounding atmosphere to decrease the first upward lifting force.

Various embodiments of the various aspects may be implemented. In someembodiments, the SPB may further comprise a barrier fluidly separatingthe first interior volume from the second interior volume. The SPB maybe configured to couple with a zero-pressure balloon (ZPB) that isconfigured to receive therein a second mass of LTA gas to provide asecond upward lifting force to the ZPB. A total mass of the first andsecond mass of LTA gas may be configured to provide from about 5% freelift to about 15% free lift at launch. The SPB may further comprise asecond adjustable valve in fluid communication with the ambient air andwith the second interior volume of the SPB, with the second adjustablevalve configured to be adjusted to release the ambient air from thesecond interior volume of the SPB to the surrounding atmosphere todecrease the downward force.

In another aspect, a method of controlling buoyancy of a high altitudeballoon system comprising a super pressure balloon (SPB) is described.The method comprises releasing a lighter than air (LTA) gas from a firstinterior volume of the SPB to a surrounding atmosphere, pumping ambientair into a second interior volume of the SPB, and releasing at least aportion of the ambient air from the second interior volume of the SPB tothe surrounding atmosphere. In some embodiments, the method furthercomprises providing the first interior volume of the SPB with the LTAgas.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several embodiments in accordance with thedisclosure and are not to be considered limiting of its scope, thedisclosure will be described with additional specificity and detailthrough use of the accompanying drawings. In the following detaileddescription, reference is made to the accompanying drawings, which forma part hereof. In the drawings, similar symbols typically identifysimilar components, unless context dictates otherwise. The illustrativeembodiments described in the detailed description, drawings, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made, without departing from the spirit or scope ofthe subject matter presented here. It will be readily understood thatthe aspects of the present disclosure, as generally described herein,and illustrated in the Figures, can be arranged, substituted, combined,and designed in a wide variety of different configurations, all of whichare explicitly contemplated and make part of this disclosure.

FIG. 1 is a perspective view of an embodiment of a lighter-than-air(LTA) system for high altitude flight including a zero-pressure balloon(ZPB), a super-pressure balloon (SPB) and a stratocraft having apayload, a parafoil descent system and supporting subsystems.

FIG. 2 is a perspective view of the ZPB of FIG. 1.

FIGS. 3A and 3B are, respectively, side and top views of the SPB of FIG.1.

FIGS. 4A and 4B are, respectively, side and top perspective views of anembodiment of a gimbal that may be used with the LTA system of FIG. 1.

FIGS. 4C and 4D are top perspective views of another embodiment of agimbal having a release mechanism that may be used with the LTA systemof FIG. 1.

FIGS. 5A and 5B are, respectively, perspective and side views of thestratocraft of FIG. 1 including embodiments of an upper craft having astowed parafoil and a payload support.

FIG. 5C is a close up view of a portion of a ladder assembly configuredto couple the payload support with the SPB such that the payload supportis located below the SPB when the balloon system is in flight.

FIG. 6 is a top perspective view of the payload support of FIGS. 5A-5Bincluding a compressor assembly.

FIGS. 7A and 7B are perspective views of the compressor assembly of FIG.6 shown in isolation from the payload support.

FIG. 8 is a perspective view of the parafoil system of FIGS. 5A and 5Bseparated from the LTA system and in a deployed flight configurationwith the payload support.

FIGS. 9A and 9B are side views of another embodiment of an LTA systemfor high altitude flight having a ZPB, an SPB and a compressor shown at,respectively, relatively lower and higher altitudes.

FIGS. 9C-9E are side views of other embodiments of LTA systems for highaltitude flight having a ZPB and either multiple SPB's or an SPBcomprising multiple compartments.

FIG. 10 is a schematic depicting an embodiment of a control system ofthe LTA system of FIG. 1 to control altitude and other parameters.

FIG. 11A is a schematic depicting embodiments of ascent and descentrates and flight ranges for the LTA of FIG. 1.

FIG. 11B is a flow chart showing an embodiment of a method for ascendingand descending with the LTA system of FIG. 1.

FIG. 12A is a schematic depicting an embodiment of a persistenceenvelope for high altitude station-keeping with the LTA system of FIG.1.

FIG. 12B is a flow chart showing an embodiment of a method forstation-keeping with the LTA system of FIG. 1.

FIG. 13A is a side view of an embodiment of an LTA system with an SPBhaving a single SPB chamber.

FIG. 13B is a side view of an embodiment of an LTA system with acontinuous two-chambered SPB having first and second SPB chambersarranged axially and with a waist fitting.

FIG. 13C is a side view of an embodiment of an LTA system with acontinuous three-chambered SPB having first, second and third SPBchambers arranged axially and with two waist fittings.

FIG. 13D is a partially broken perspective view of an embodiment of acontinuous five-chambered SPB having first, second, third, fourth andfifth SPB chambers arranged axially and with four waist fittings.

FIG. 14A is a side view of the two-chambered SPB of FIG. 13B and havingapex and nadir fittings.

FIG. 14B is a side view of the three-chambered SPB of FIG. 13C andhaving apex and nadir fittings.

FIG. 14C is an embodiment of a gore, shown in a flat configuration, thatmay be used with the continuous two-chambered SPB of FIG. 13A.

FIG. 14D is a cross-section view of the two-chambered SPB of FIG. 13Ataken along the line 14D-14D as indicated in FIG. 14A.

FIGS. 15A and 15B are cross-section views of an embodiment of acontinuous two-chambered SPB having two internal air compartmentsseparated by a bladder and shown, respectively, with the bladder in afirst and second configuration.

FIG. 15C is a cross-section view of an embodiment of a continuousthree-chambered SPB 300 having two internal air compartments separatedby a bladder.

FIGS. 15D and 15E are cross-section views of an embodiment of acontinuous two-chambered SPB having two internal air compartmentsseparated by a bladder and shown, respectively, with the bladder in afirst and second configuration.

FIGS. 16A-16B are side views of embodiments of respectively alaterally-arranged multi-chamber SPB and a multi-chamber SPB withinterspersed compressors.

FIG. 17A is a wire frame view of an embodiment of a continuoustwo-chambered SPB having a waist fitting.

FIG. 17B is a detail view of the interior of the SPB of FIG. 17A at thewaist and showing the waist fitting.

FIG. 18A is a perspective view of an embodiment of a waist fitting thatmay be used with the various multi-chamber SPB's described herein.

FIG. 18B depicts the waist fitting of FIG. 18A with a portion removedfor clarity.

FIG. 18C is a cross-section view of the waist fitting of FIG. 18A.

FIG. 18D is a cross-section view of the waist fitting of FIG. 18A shownwith radially extending tendons 330.

FIG. 18E is a cross-section view of the waist fitting of FIG. 18A, witha portion removed for clarity, and shown with radially extendingtendons.

FIG. 18F is a cross-section view of the waist fitting of FIG. 18A shownwith axially extending tendons.

FIG. 18G is a cross-section view of the waist fitting, with a portionremoved for clarity, and shown with axially extending tendons.

FIG. 19A is a perspective view of an embodiment of an SPB having annulusend pieces at the apex and nadir of the SPB.

FIG. 19B is a perspective view of an embodiment of an end interface thatmay be used at the nadir and/or apex of the various SPB's describedherein.

FIG. 19C is a perspective view of an SPB having the interface of FIG.19B at the apex and nadir of the SPB.

FIG. 19D shows an embodiment of a fitting assembly at an apex of theSPB.

FIG. 19E shows an embodiment of a fitting assembly at a nadir of theSPB.

FIGS. 20A-20C depict schematics of embodiments of a system and methodfor constructing a rope ring waist fitting.

FIG. 21 is a side view an embodiment of an LTA system having an SPBcontaining a lifting gas.

FIGS. 22A and 22B are side views of embodiments of LTA systems havingalternative continuous multi-chamber SPB arrangements with at least oneSPB chamber containing a lifting gas.

FIG. 23 is a side view of an embodiment of an LTA system stood up on theground ready for launch and having two super pressure envelopes showingone envelope relatively more inflated than the other.

FIGS. 24A, 24B and 24C depict embodiments of various altitude controltechniques with the various LTA systems described herein, includingamong others neutral buoyancy, descent and ascent.

DETAILED DESCRIPTION

The following detailed description is directed to certain specificembodiments of the development. Reference in this specification to “oneembodiment,” “an embodiment,” or “in some embodiments” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one embodiment of theinvention. The appearances of the phrases “one embodiment,” “anembodiment,” or “in some embodiments” in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments necessarily mutuallyexclusive of other embodiments. Moreover, various features are describedwhich may be exhibited by some embodiments and not by others. Similarly,various requirements are described which may be requirements for someembodiments but may not be requirements for other embodiments.

Various embodiments will now be described with reference to theaccompanying figures, wherein like numerals refer to like elementsthroughout. The terminology used in the description presented herein isnot intended to be interpreted in any limited or restrictive manner,simply because it is being utilized in conjunction with a detaileddescription of certain specific embodiments of the development.Furthermore, embodiments of the development may include several novelfeatures, no single one of which is solely responsible for its desirableattributes or which is essential to practicing the invention describedherein.

One possible limiting factor for lighter-than-air (LTA) systems is theinability to effectively control the trajectory while in flight. Forinstance, some applications require the ability to ascend and descend atfast rates, to ascend and descend over large altitude ranges, tomaintain station-keeping envelopes for extended periods of time, tomaintain constellation coverage, etc. However, existing LTA systems donot provide simple and inexpensive solutions to achieve these and otheradvanced performance targets. There is, therefore, a need for such LTAsystems and methods. Embodiments of the present disclosure address theseand/or other challenges.

Described herein are systems and devices for high altitude flight usingLTA systems having tandem balloons. A zero-pressure balloon (ZPB) thatprovides lift is attached in tandem with one or more variable airballast super-pressure balloons (SPB). The SPB provides a controlled andvariable air ballast supply and emission (i.e. two-way ballast control)from ambient air in the surrounding atmosphere. A compressor, withsufficient air volume flow rate capabilities, provides sufficientambient air to the SPB even at low densities in high altitudes for rapiddescent or altitude maintenance. A controllable valve is sized andcontrolled for sufficient air release from the SPB for rapid ascent oraltitude maintenance. These and other features of the LTA system allowfor performance of advanced navigation and altitude control techniques.The LTA systems described herein are more agile, require less power andweigh less than existing balloon system solutions for similar missionrequirements. The LTA system thus allows for performance of advancedmaneuvers at high altitude, allowing for a multitude of high altitudeLTA system uses—and with a single, scalable platform. Described hereinare some embodiments of the LTA system and of some example methods ofusing the system, including rapid ascent/descent and station-keeping tomaintain a persistence envelope at high altitudes. Thus, the LTA systemhas various other embodiments and is capable of many other uses, even ifnot explicitly described herein.

As used herein, “high altitude” refers to altitudes that are in thestratosphere (above 35,000 feet), and includes without limitationaltitudes in the troposphere, the tropopause, and the stratosphere ofEarth's atmosphere. The altitude range for “high altitude”, for examplein terms of kilometers or miles, will vary depending on the latitude andlongitude. In some locations, high altitude will include a range ofabout 30,000 feet to about 120,000 feet or 130,000 feet. The exactaltitude of flight desired depends on the wind distribution and thetrajectory one is seeking. High altitude can also refer to altitudes ofnon-Earth atmospheres on other planets with atmospheres that may notfall within the given altitude range on Earth. Further, descriptionherein of a system as “high altitude” is not meant to exclude flight ofthat system through lower altitudes, for example during takeoff fromground and ascent to higher altitudes or descent and landing on theground.

A. LTA System

FIG. 1 is a perspective view of an embodiment of a lighter-than-air(LTA) system 100 for high altitude flight. For reference, a longitudinalaxis 105 is indicated. The longitudinal axis 105 is a reference axis fordescribing the system 100. Directions described as “outer,” “outward,”and the like, are referring to a direction at least partially away fromsuch longitudinal axes, while directions described as “inner,” “inward,”and the like, are referring to a direction at least partially towardsuch longitudinal axes.

For reference, a +Z direction is indicated that is opposite in directionto that of gravity, and a −Z direction is indicated that is opposite indirection to the +Z direction. For the sake of description, directionsdescribed as “upper,” “above,” and the like, are referring to adirection at least partially in the +Z direction, and directionsdescribed as “lower,” “below,” and the like, are referring to adirection at least partially in the −Z direction. The +Z direction isthe general direction the system 100 travels when ascending, while the−Z direction is the general direction the system 100 travels whendescending. The direction of ascent and descent of the system 100 maynot be aligned with, respectively, the +Z and −Z directions. Forexample, the system 100 may travel at an angle with respect to the +Zand −Z directions. Further, the longitudinal axis 105 may or may notalign with the +/−Z directions and/or with the direction of travel ofthe system 100.

The LTA system 100 is shown in flight. Various features of the system100 may change configuration, for example shape, geometry or dimensions,depending on the phase of a mission (e.g. takeoff, flight, landing).Thus, the depiction of the system 100 in any one configuration is notmeant to limit the disclosure to that particular configuration. Further,the basic design of the LTA system 100 may be adapted, for examplescaled, modularized, etc. for different mission requirements. The LTAsystem 100 can be modularized, for example with multiple SPB's 300 suchas in tandem pneumatically connected to each other, as furtherdescribed. The description herein is primarily of a very high altitudeand/or heavy payload lifting version of the LTA system 100, unlessotherwise stated. Therefore, other configurations, of the basic platformfor the particular LTA system 100 described herein, are within the scopeof this disclosure even if not explicitly described.

The LTA system 100 includes a zero-pressure balloon (ZPB) 200, asuper-pressure balloon (SPB) 300 and a stratocraft 400. The SPB 300 maybe a single chamber as shown or may include multiple chambers, asfurther described herein. The ZPB 200, SPB 300 and the stratocraft 400are shown coupled together. In some phases of flight, the ZPB 200, SPB300 and the stratocraft 400 are not coupled together. For example,portions of the stratocraft 400 may release from the LTA system 100,such as during descent of a payload and descent system. As furtherexample, the ZPB 200, SPB 300 and/or the stratocraft 400 may separatefrom each other after flight termination.

The ZPB 200 is a lifting balloon. The primary function of the ZPB 200 isto provide lift to the LTA system 100. A lighter-than-air (LTA) gas isprovided inside the ZPB 200 in an amount at launch sufficient for theLTA system 100 to take off. The ZPB 200 will initially be under-inflatedbut with sufficient lifting capacity in a collapsed configuration atlaunch from ground, and will expand as the LTA system 100 ascends tohigher altitudes with lower pressure air.

The ZPB 200 is a “zero-pressure” type of balloon. A “zero-pressureballoon” contains an LTA gas therein for providing lift to the LTAsystem 100. The ZPB 200 may be filled with helium or hydrogen. A“zero-pressure balloon” is normally open to the atmosphere via hangingor attached ducts to prevent over-pressurization. If flying alone as asingle ZPB 200, the ZPB 200 would be susceptible to the cyclic increaseand decrease in altitude caused by the constant balloon envelope volumechange due to heating and cooling, and therefore expansion andcontraction of the lift gas inside the ZPB 200 throughout the Earth'sdiurnal cycle. This constant altitude change leads to the loss of liftgas over time as the heating of the lift envelope during the day cyclecauses the lift gas to expand until the maximum float altitude isreached and the LTA gas is vented out of the opening in the ZPB 200.During the night cycle, the lift gas contracts, causing the ZPB 200envelop to contract and lose buoyancy. For this reason the LTA system100 controls the natural changes of buoyancy as well having the abilityto bias the buoyancy even more than simply neutralizing the naturalchanges in order to achieve controlled altitude changes. Particularembodiments and other aspects of the ZPB 200 are described in furtherdetail herein, for example with respect to FIG. 2.

The ZPB 200 supports the SPB 300. As shown, the SPB 300 is supportedunderneath the ZPB 200. The ZPB 200 may support the SPB 300 eitherdirectly or indirectly, for example via a rotatable actuator, asdescribed herein. Particular embodiments of rotatable connectionsbetween the ZPB 200 and SPB 300 are described in further detail herein,for example with respect to FIGS. 4A-4B.

The SPB 300 is a variable air ballast balloon. The primary function ofthe SPB 300 is to provide a variable amount of ballast to the LTA system100. Ballast is taken into the SPB 300 in the form of compressed air toprovide a greater downward force to the LTA system 100. Ballast isejected from the SPB 300 to provide a smaller downward force to the LTAsystem 100. The ballast is provided from the ambient atmospheric air,for instance by a compressor, as described in further detail herein, forexample with respect to FIGS. 6-7. To achieve neutral buoyancy the airballast can be set at some fraction of the SPB 300 maximum pressurecapability. This allows biasing in both a positive (greater air ballast)and negative direction (less air ballast) which leads to a descent speedor ascent speed respectively. In some embodiments, the LTA system 100includes only one SPB 300 or one SPB 300 with a single chamber. However,the LTA system 100 can include multiple SPB's 300 or a single SPB 300having multiple chambers, for example, two, three, four or more SPB's300 and/or chambers, as further described herein, for example withrespect to FIGS. 9C-9E.

The SPB 300 is a “super-pressure” type of balloon. A “super-pressureballoon” is completely enclosed and operates at a positive internalpressure in comparison to the external atmosphere. Pressure controlenables regulating the mass of air in the SPB 300, and therefore theoverall buoyancy of the LTA system 100. This buoyancy regulation enablesaltitude control of the LTA system 100. The SPB 300 may take in more airto apply more of a ballast force, for example to descend, or tocompensate for an expanding ZPB 200 that is producing more lift, asdescribed. Conversely, the SPB 300 may release air to apply less of aballast force, for example to ascend, or to compensate for a contractingZPB 200 that is producing less lift, as described. Particularembodiments and other aspects of the SPB 300 are described in furtherdetail herein, for example with respect to FIGS. 3A-3B.

The SPB 300 supports the stratocraft 400. As shown, the stratocraft 400is coupled with the SPB 300 beneath the SPB 300. The stratocraft 400 maybe directly or indirectly connected with the SPB 300. In someembodiments, there are various intermediate structures and/or systemsbetween the SPB 300 and the stratocraft 400, such as structuralconnectors, release mechanisms, other structures or systems, orcombinations thereof.

The stratocraft 400 includes one or more systems related to variousmission objectives. The stratocraft 400 may include the payload for aparticular mission. The stratocraft 400 may include various subsystems,such as power, control, communications, air intake, air release, payloaddescent, etc., for supporting a mission. Particular embodiments of thestratocraft 400 are described in further detail herein, for example withrespect to FIGS. 5A-5B. Some embodiments of particular payloads,supporting payload structures, air intake/release subsystems, andpayload descent subsystems, are described in further detail herein, forexample with respect to FIGS. 6-8.

B. Zero Pressure Balloon

FIG. 2 is a perspective view of the ZPB 200. ZPB 200 provides a liftforce in the +Z direction, as indicated. For reference, a geometriclongitudinal axis 205 of the ZPB 200 is indicated. The longitudinal axis205 may or may not align with the +Z direction, depending on the phaseof flight, environmental conditions, etc. Further, the ZPB 200 may notcause the LTA system 100 to travel exactly in the +Z direction. Thus,while the lift force is in the +Z direction, the LTA system 100 may nottravel in that same direction. In some embodiments, the LTA system 100ascends in a direction that is at an angle to the +Z direction.

The ZPB 200 includes an upper portion 210 having a top 212 and a lowerportion 215 having a bottom 217. The upper portion 210 refers to a partof the ZPB 200 that is above the lower portion 215. The upper and lowerportions 210, 215 may be the upper and lower halves of the ZPB 200. Theupper and lower portions 210, 212 may be symmetric about thelongitudinal axis 205, for example when the ZPB 200 is fully inflated atits maximum volume altitude, such as in higher altitudes with less densesurrounding atmosphere. The dimensions of the ZPB 200 when upright andfully inflated may be about 100 feet wide and about 95 feet high. TheZPB 200 may have a range of widths from about 75 feet or less to about370 feet or more. The ZPB 200 may have a range of heights from about 70feet or less to about 310 feet or more.

The ZPB 200 includes a skin 220. The skin 220 forms the upper and lowerportions 210, 215 of the ZPB 200, or sections thereof. The skin 220 isassembled to form the outer body of the ZPB 200. The skin 220 may beabout 0.0008 inches thick. Various versions of the ZPB 200 may have arange of thicknesses of the skin 220 from about 0.00025 inches or lessto about 0.0015 inches or more thick. The skin 220 may have a generallyuniform thickness over most or all of the ZPB 200. In some embodiments,the thickness of the skin 220 may vary depending on the location of theskin 220 about the ZPB 200. The basic skin is known as the “shell”, andif extra thickness is required for structurally containing the liftbubble at launch, those extra layers are known as “caps”. Caps areusually some fraction of the gore length covering the top of the shelland usually are no longer than 50% of the gore length, although thischanges depending on the design altitude.

The skin 220 defines one or more interior compartments of the ZPB 220for receiving an LTA. In some embodiments, the ZPB 200 is configured toreceive therein an LTA gas to provide an upward lifting force to the LTAsystem 100. The ZPB 200 may include about 500,000 cubic feet of maximuminternal volume. Various versions of the ZPB 200 may include a rangefrom about 250,000 cubic feet or less to about 30,000,000 cubic feet ormore of maximum internal volume. The ZPB 200 may include sufficient liftgas to lift the gross weight of the vehicle plus additional “free lift”which can range from 5% of the gross weight to about 25% of the grossweight depending on the application. The volume of the launch “bubble”is a fraction of the maximum design volume and usually ranges from 1/20to 1/200 of design volume depending on design altitude.

The skin 220 may be formed from a variety of materials. In someembodiments, the skin 220 is formed from plastic, polymer, thin films,other materials, or combinations thereof. The skin 220 may be made frommultiple components. As shown, the skin 220 includes gores 925. The skin220 may be configured with gores 925, other suitable approaches, orcombinations thereof. The gores 925 are elongated sections of balloonmaterial. The gores 925 may extend to the top 212 and/or to the bottom217. In some embodiments, the gores 925 do not extend to the top 212and/or to the bottom 217. For example, the skin 220 may be formed ofgores 925, with endcaps surrounding upper and lower ends of the gores925 at the top 212 and/or bottom 217. In some embodiments, the bottom217 of the ZPB 200 is open and the lower ends of the gores 925 extend toor near the opening formed at the bottom 217.

The ZPB 200 changes configuration (shape, size, etc.) during flight asthe lift gas volume expands and contracts. The skin 220 or portionsthereof may change configuration due to launch requirements, variableair pressure, changes in volume of LTA, release of payload and descentsystems, flight termination, etc.

C. Super Pressure Balloon

FIGS. 3A and 3B are, respectively, side and top views of the SPB 300.The SPB 300 provides a downward ballast force in the −Z direction, asindicated. For reference, a geometric longitudinal axis 305 of the SPB300 is indicated. The longitudinal axis 305 may or may not align withthe −Z direction, depending on the phase of flight, environmentalconditions, etc. Further, the SPB 300 may not cause the LTA system 100to travel exactly in the −Z direction. Thus, while the downward force isin the −Z direction, the LTA system 100 may not travel in that samedirection. In some embodiments, the LTA system 100 descends in adirection that is at an angle to the −Z direction, which may be mostlydue to wind. In some embodiments, the force due to lift from the ZPB 200is greater than the combined downward force due to gravity exerted bythe entire LTA system 100, including the weight of the ZPB 200, theweight of the SPB 300, the weight of the stratocraft 400, etc. such thatthe LTA system 100 ascends in a direction that is at least partially inthe +Z direction. In some embodiments, the force due to lift from theZPB 200 is less than the combined downward force due to gravity exertedby the entire LTA system 100, including the weight of the ZPB 200, theweight of the SPB 300, the weight of the stratocraft 400, etc. such thatthe LTA system 100 descends in a direction that is at least partially inthe −Z direction.

The SPB 300 includes an upper portion 310 having a top 312 and a lowerportion 315 having a bottom 317. The upper portion 310 refers to a partof the SPB 300 that is above the lower portion 315. The upper and lowerportions 310, 315 may be the upper and lower halves of the SPB 300. Theupper and lower portions 310, 312 may not be separate parts, but may beportions of the same continuous skin of the SPB 300 used for descriptionherein. The upper and lower portions 310, 312 may be symmetric about thelongitudinal axis 305, for example when the SPB 300 is fully inflatedwhen pressurized, which may be in higher altitudes with less denseatmosphere. The axis 305 of the SPB 300 may align with and/or beparallel to the axis 205 of the ZPB 200. In some embodiments, the axis305 of the SPB 300 may not align with and/or not be parallel to the axis205 of the ZPB 200. In some embodiments, the axis 305 of the SPB 300 mayalign with and/or be parallel to the axis 205 of the ZPB 200 during somephases of a flight, and the axis 305 of the SPB 300 may not align withand/or not be parallel to the axis 205 of the ZPB 200 during otherphases of a flight.

The maximum dimensions of the SPB 300, for example when fully inflated,may be about 56 feet wide in diameter and about 35 feet long in height.The SPB 300 may have a range of maximum diameters from about 10 feet orless to about 500 feet or more. The SPB 300 may have a range of maximumlengths from about 5 feet or less to about 300 feet or more.

The SPB 300 includes a skin 320. The skin 320 forms the upper and lowerportions 310, 315 of the SPB 300, or sections thereof. The skin 320 isassembled to form the outer body of the SPB 300. The skin 320 may beabout 0.004 inches thick. Various versions of the SPB 300 may have arange of thicknesses of the skin 220 from about 0.0015 inches to about0.008 inches thick. The skin 320 has a generally uniform thickness overmost or all of the SPB 300. In some embodiments, the thickness of theskin 320 may not be uniform and may vary depending on the location ofthe skin 320 about the SPB 300.

The skin 320 defines one or more interior compartments of the SPB 300for receiving and storing ambient air. In some embodiments, the outerskin 320 defines an interior volume of the SPB 300 configured to receivetherein a variable amount of ambient air from a surrounding atmosphereto provide a variable downward force to the LTA system 100. The SPB 300may have a maximum internal volume of about 64,000 cubic feet. Variousversions of the SPB 300 may include a range from about 32,000 cubic feetor less to about 90,000 cubic feet or more of maximum internal volume.

The skin 320 may be formed from a variety of materials. In someembodiments, the skin 320 is formed from plastic, polymer, thin films,other materials, or combinations thereof. The skin 320 may be made frommultiple components. As shown, the skin 320 includes gores 325. The skin320 may be configured with gores 325, other suitable approaches, orcombinations thereof. The gores 325 are elongated sections of balloonmaterial. The gores 325 may extend to the top 312 and/or to the bottom217. In some embodiments, the gores 325 do not extend to the top 312and/or to the bottom 317. For example, the skin 320 may be formed ofgores 325, with endcaps surrounding upper and lower ends of the gores325 at the top 312 and bottom 317.

The SPB 300 includes multiple tendons 330. The tendons 330 are elongatedflexible members. The tendons 330 may be axially-stiff,transverse-flexible rope-like members. The tendons 330 may be formed offiber, composites, plastic, polymer, metals, other materials, orcombinations thereof. The tendons 330 may have a denier of about 61,000.The tendons 330 may have range of deniers from about 10,000 to about200,000. The tendons 330 may have a thickness of about 0.125 inch. Thetendons 330 may have a thickness of 0.125 inch. The tendons 330 may haverange of thicknesses from about 0.05 inches or less to about 0.5 inchesor more. The tendons 330 may include covers or sheaths, either partiallyor entirely. The tendons 330 extend along the outside of the skin 320.The tendons 330 may extend from or near the top 312 to or near thebottom 317 of the SPB 300. The tendons 330 are meridonially configured,extending meridonially along the SPB 300. The tendons 330 may beseparate from each other. In some embodiments, some or all of thetendons 330 may be coupled together. In some embodiments, some or all ofthe tendons 330 may form one continuous, long tendon. In someembodiments, the LTA system 100 includes a plurality of the tendons 330coupled with the SPB 300 and extending along an exterior of the outerskin 320 of the SPB 300 and configured to bias the SPB 300 into apumpkin-like shape at least when the SPB 300 is pressurized relative tothe surrounding atmosphere, for instance when a first pressure insidethe SPB 300 is greater than a second pressure of the surroundingatmosphere.

The SPB 300 may include tape 335. The tape 335 may be an adhesivematerial. The tape 335 may couple sections of the skin 320, such as thegores 325, together. The tape 335 may extend along edges of the gores325. The tape 325 may extend underneath or generally near the tendons330. In some embodiments, a segment of tape 325 extends underneath acorresponding segment of tendon 335. The tape 335 may extend to or nearthe top 312 and/or to or near the bottom 317 of the SPB 300.

The SPB 300 changes configuration (shape, size, etc.) during flight. Theskin 320, tendons 330, and/or tape 335, or portions thereof, may changeconfiguration due to launch requirements, variable air pressure, changesin volume of LTA, release of payload and descent systems, flighttermination, pressurization with a compressor, etc. In some embodiments,the SPB 300 may be configured to take a particular shape during flight,such as a “pumpkin” shape or other shapes, as described herein.

The SPB 300 is shown with bulges 340. The bulges 340 are portions of theskin 320 that are located farther outward than adjacent portions of theskin 320. For example, the bulges 340 may be curved portions of thegores 325 that are located farther radially from the longitudinal axis305 than adjacent portions of longitudinal edges of the gores 325. Thebulges 340 may refer to portions of the skin 320 that are locatedfarther outward than adjacent tendons 330 and/or tape 335. The bulges340 may assist with forming part of the pumpkin shape of the SPB 300.This is a natural structural result of pressurizing the film while in ameridionally-reinforced multi-gore configuration.

The SPB 300 may be configured based on maximization of a performanceratio R defined by R=[ΔP×V]/M. Here, “ΔP” is the differential pressurebetween the internal pressure of the SPB 300 and the ambient pressure ofthe immediately surrounding atmosphere, “V” is the maximum internalvolume of the SPB 300 when assuming an inflated shape, and “M” is thegross mass of the LTA system 100 structure (e.g. the total mass of theZPB 200, the SPB 300, the stratocraft 400, and other structural featuresof the LTA system 100, but not including the mass of any internal air orlift gas in the various balloons). In some embodiments, ΔP is about 3500Pa. In some embodiments, ΔP is 3500 Pa, 5000 Pa, 7500 Pa, 10,000 Pa, or12,000 Pa. Depending on the embodiment, AP may be within a range fromabout 750 Pa or less to about 12,000 Pa or more. In some embodiments, Vis as described above regarding the internal volume of the SPB 300. Insome embodiments, M is about 600 kilograms. Depending on the embodiment,M may be within a range from about 125 kilograms or less to about 2,000kilograms or more.

The performance ratio R may be maximized with various configurations ofthe system 100. For example, the “Pumpkin” configuration of the SPB 300,as further described herein, allows for a large “ΔP” and “V” with asmaller “M,” which increases the ratio “R.” As further example, anefficient intake and release of air allows for quickly filling the large“V” to perform the advanced maneuvers and missions. Features forachieving such efficient intake and release of air are described infurther detail herein, for example with respect to FIGS. 6-7.

The SPB 300 may be in a “pumpkin” shape. The pumpkin shape may includethe multiple bulges 340, a flattened top 312, a flattened bottom 317,and/or non-circular lateral cross-sections of the skin 320 (i.e.cross-sections of the skin 320 taken along a plane that includes thelongitudinal axis 350). The skin 320 and accessories such as the tendons330, tape 335, etc. may be designed to achieve the pumpkinconfiguration.

The SPB 300 may be designed to withstand large internal pressures whilealso providing structural stability at such large pressures. As furtherdiscussed herein, larger internal pressures of the SPB 300 allow forperforming advanced maneuvers and achieving advanced mission goals withthe system 100. However, large internal pressures of the SPB 300 maycause problems with structural integrity, stability, etc. For instance,“S-clefting” is a serious global geometric shape instability to whichpumpkin-shaped balloons are susceptible. S-clefting can result in theskin 320 locally buckling and bunching together along a continuous curvefrom top to bottom, resulting in the general shape of an “S” on theballoon's surface. S-clefting may be caused by an excess of skin 320material in the equatorial region, for example in the middle portion311. The pumpkin shape may contribute to such concentration of material,for instance by having a well-rounded bulge-lobe angle. To imagine whatis meant by bulge angle, consider a circle. Draw a line from a point onthe circle to the center, then back out to another point on the circlenot too far away from the first point. The angle of the “V” that wasjust drawn is the bulge angle, and the arc between the two pointsrepresents the shape of the gore bulge, or lobe. The reason to have thewell-rounded bulge 340 (small bulge radii) is that it lowers the hoopstress in the skin 320 which allows for higher differential pressures inthe SPB 300 without reaching the burst point. For instance, the pressureloads may be more efficiently transferred to the tendons 330, which mayextend along the valleys 342 between the bulges 340. This beneficialstress-lowering effect however has a limit where too much material leadsto the s-cleft instability.

The S-cleft depends in part on the number of gores 325 and the flatnessof the bulges 340. “Flat” here refers to a smaller radial distancebetween the outermost and innermost portions of a given bulge 340(smaller bulge angle). Flatter bulges 340 reduce the concentration ofmaterial around the balloon's middle portion 311 thus reducing theS-cleft susceptibility, but they also increase the hoop stress thusreducing the internal pressure capability. Further, a greater number ofgores 325 reduces the load per tendon, but increases the S-cleftsusceptibility. Thus, the number of gores 325, the flatness of thebulges 340, and the overall “pumpkin” shape are configured so the SPB300 can withstand a high internal pressure while preventing structuralinstabilities such as S-clefting. The skin thickness, the designdifferential pressure, the arc angle of the gore bulges (“bulge angle”),strength and stiffness of the tendons, and the number of gores (andtherefore number of tendons) have to be carefully balanced in the designprocess to not exceed the strength of the structural elements and to nothave global shape instabilities called “s-clefts”.

D. Rotatable Actuator

FIGS. 4A and 4B are perspective views of an embodiment of a gimbal 500that may be used with the LTA system 100. The ZPB 200 and SPB 300 may becoupled together directly or indirectly, as mentioned. As shown in FIG.4A, the ZPB 200 and SPB 300 are coupled together indirectly via thegimbal 500. The gimbal 500 is coupled, for example structurallyattached, with the bottom 217 of the ZPB 200 and the top 312 of the SPB300. The gimbal 500 provides for rotation of the SPB 300 relative to theZPB 200 about the longitudinal axis 105. In some embodiments, the gimbal500 may provide for rotation about an axis that is not aligned and/orparallel to the longitudinal axis 105. Further, the gimbal 500 may be arotatable actuator configured for rotation about more than one axis.

The gimbal 500 may be coupled with various features of the respectiveballoons. As shown in FIG. 4B, the gimbal includes a lower bracket 502attached to a plate 314 of the SPB 300. The top 312 of the SPB 300includes the plate 314 attached to an apex of the SPB 300. The apex 313may be a portion of the skin 320 at the top 312 of the SPB 300. Theplate 314 is a structural fitting attached to the apex 313. The lowerbracket 502 of the gimbal 500 is attached to the plate 314 via fasteners504, such as bolts. Other suitable connectors, in addition oralternatively to fasteners 504, may be used. The gimbal 500 may alsoinclude standoffs 506. The standoffs 506 are structural separators thatprovide spacing between the gimbal (e.g. the lower bracket 502) and theSPB 300 (e.g. the plate 314). There may be a series of the fasteners 504and/or the standoffs 506 in various locations.

The gimbal 500 may include a motor 510. The motor 510 causes movement ofportions of the gimbal 500. The motor 510 may be a variety of differentsuitable motion actuators. In some embodiments, the motor 510 is anelectric, combustion, or other type of motor. The motor 510 may outputrotation at a speed of about 5 rpm. Depending on the embodiment, themotor 510 may output rotation within a range of about 1 rpm or less toabout 20 rpm or more. The motor 510 may be reversible. For instance, themotor 510 may be configured to cause movement in a first direction andin a second direction that is opposite the first direction. In someembodiments, the motor 510 can rotate clockwise as well ascounterclockwise.

The gimbal 500 further includes a first gear 515. The first gear 515 isrotated by the motor 510. The first gear 515 may be rotatably mounted onan end of an axle of the motor 510. The gimbal 500 further includes asecond gear 520. The second gear 515 is rotatably coupled with the lowerbracket 502. The second gear 520 is in mechanical communication with thefirst gear 515, such that rotation of the first gear 515 causes rotationof the second gear 520. The second gear 520 may have a larger diameterthan the first gear 515. The first and second gears 510, 520 may becircular as shown. The first and second gears 510, 520 may be formedfrom various suitable materials, such as metals, other materials, orcombinations thereof.

The gimbal 500 may include one or more connectors 525. As shown, theremay be three connectors 525. The connectors 525 are structuralconnections. As shown, the each connector 525 may have an elongatedmember 527 with attachments 529 on upper and lower ends of the connector525. The elongated member 527 may have a cylindrical cross-section. Theattachments 529 on the lower end of the connector 525 connect with thesecond gear 520. Rotation of the second gear 520 moves the connectors525 along a corresponding circular path. The attachments 529 on theupper end of the connectors 525 connect with an upper bracket 530. Theupper bracket 530 is a structural attachment, and may be formed from avariety of suitable materials, including metals, other materials, orcombinations thereof. The upper bracket 530 couples with the ZPB 200.For example, the upper bracket 530 may be structurally attached,directly or indirectly, to the bottom 217 of the ZPB 200, usingfasteners, etc.

The connectors 525 may assist with dynamic stability of the system 100.For example, the ZPB 200, SPB 300 or other parts of the system 100 (e.g.the stratocraft 400) may be more susceptible to, or subject to, adisturbance, such as a wind gust, weather, or other environmentalfactors. The connectors 525 may assist with compensating for anyresulting movement of the SPB 300 relative to the ZPB 200. Theconnectors 525 may provide such flexibility in any direction, includingaxially in the +/−Z direction, at an angle to the +/−Z direction, etc.

The connectors 525 may assist with lateral stiffness of the system 100by providing a flexible or movable connection between the ZPB 200 andthe SPB 300. In some embodiments, the connectors 525 or portions thereofmay be formed from flexible materials, such as metals, composites, othersuitable materials, or combinations thereof. In some embodiments, themember 527 of each connector 525 is formed from such flexible materials.In some embodiments, the connectors 525 may have flexible attachmentswith the gimbal 500 and/or the ZPB 200 allowing for some movement. Forinstance, the attachments 529 may allow for rotation of the attachments529 relative to the upper bracket 530 and/or second gear 520 aboutparticular axes, for example about axes not aligned with the axis ofrotation of the gimbal 500. As further example, the members 527 may berotatably coupled with the corresponding attachments 529 for thatconnector 525. This may allow for relative rotation between the members527 and the attachments 529. These and other features may assist withisolating undesirable relative movement between the ZPB 200 and the SPB300, while allowing for desirable rotation of the SPB 300, as describedherein.

Rotation of the gimbal 500 causes relative rotation between the ZPB 200and the SPB 300. Rotation of the SPB 300 may be desirable for pointing asolar array 630, as further described herein, for example with respectto FIGS. 5A-5B. For example, the gimbal 500 may be configured to rotatethe SPB 300 relative to the ZPB 200, wherein the SPB and the solar array630 are rigidly coupled with an elongated ladder assembly 610 such thatrotation of the SPB 300 with the gimbal 500 rotates the elongated ladderassembly 610 and the solar array 630 to a desired orientation. In someembodiments, the gimbal 500 has sufficient torsional stiffness andcontrol authority to point the payload support 700 (e.g., via rotationof the SPB 300 that is coupled with the payload support 700) in adesired direction and maintain that directional pointing despite naturalor induced atmospheric disturbances to or flows over the LTA system 100.

In some embodiments, both the ZPB 200 and the SPB 300 rotate uponactuation of the gimbal 500. The ZPB 200 and the SPB 300 may rotate inopposite directions upon actuation of the gimbal 500. In someembodiments, the gimbal 500 may be rigidly coupled with both the ZPB 200and the SPB 300 such that rotation of the gimbal 500 is transmitted toboth the ZPB 200 and the SPB 300. The couplings between the gimbal 500and the ZPB 200 and the SPB 300 may allow for rotation about thelongitudinal axis 105. In some embodiments, the gimbal 500 may includethe flexible connectors 525 and/or rotatable connections between themembers 527 and attachments 529, as described above, for dynamicstability but still allow for rotation about the longitudinal axis 105.

The gimbal 500 may cause relative rotation of the ZPB 200 and the SPB300 at various speeds. In some embodiments, the gimbal 500 causesrelative rotation of the ZPB 200 and the SPB 300 at a speed of about 24degrees per second. Depending on the embodiment, the gimbal 500 maycause relative rotation of the ZPB 200 and the SPB 300 within a range ofspeeds from about 1 degree per second or less to about 96 degrees persecond or more.

The gimbal 500 may prevent or mitigate rotation of the SPB 300 relativeto the ZPB 200. For example, the gimbal 500 may be locked so that norotation is transmitted. In some embodiments, the first gear 515 may belocked such that the second gear 520, which is in mechanicalcommunication with the first gear 515, is also prevented from moving. Asfurther example, the gimbal 500 may be locked and automatically unlockupon application of a threshold force. In some embodiments, the motor510 may allow for rotation if a rotational force is transmitted to thefirst gear 515. For instance, disturbances to the system 100 may causethe ZPB 200 to rotate relative to the SPB 300. If such disturbancestransmit large rotational forces to the gimbal 500, the gimbal 500 mayallow for such rotations to prevent structural failure to the gimbal500. For example, the motor 510 may be locked but allow for rotation ofthe first gear 515 upon application of a threshold rotational force,which may prevent damage to the first or second gears 515, 520, or toother components of the system 100.

The gimbal 500 may include a tear line 535. The tear line 535 comprisesa rope, wire or other structural connector that connects the gimbal 500,or portions thereof, to one or more gores of the ZPB 200. One end of thetear line 535 may be connected to one of the attachments 529 and theopposite end of the tear line 535 may be connected to the ZPB 200, suchas one of the gores 925 at or near the upper portion 210 of the ZPB 200.The tear line 535 may facilitate “goring” of the ZPB 200 for flighttermination, as described herein. For example, at the end of a mission,the gimbal 500 and SPB 300 may detach from the ZPB 200, and the fallinggimbal 500 and SPB 300 may cause the tear line 535 to rip one or more ofthe gores 925, and/or other portions of the skin 220, from the ZPB 200.By tearing the gores 925, the lift gas of the ZPB 200 will escape to theatmosphere, causing the ZPB 200 to fall to ground. Further details ofthe tear line 535 are described herein, for example with respect toFIGS. 4C and 4D.

FIGS. 4C and 4D are top perspective views of another embodiment of agimbal 501 that may be used with the LTA system 100. The gimbal 501 mayhave all or some of the same or similar features and/or functionalitiesas the gimbal 500, and vice versa. Thus, for example, the gimbal 501 maycouple the ZPB 200 to the SPB 300, provide for rotation of the SPB 300relative to the ZPB 200, etc. Further, the gimbal 501 includes a releasemechanism 503. The release mechanism 503 provides for separation of theSPB 300 from the ZPB 200 in flight, for example at high altitudes. Therelease mechanism 503 may provide for the gimbal 501, or portionsthereof, to release from the ZPB 200. In some embodiments, the gimbal501, or portions thereof, may be attached to the SPB 300 after actuationof the release mechanism 503. The release mechanism 503 may also providefor termination of flight of the ZPB 200 and/or SPB 300, for example bygoring the ZPB 200, as described herein.

The release mechanism 503 includes one or more release lines 526. Asshown, there are three release lines 526. There may be fewer or morethan three release lines 526, for example one, two, four, five, six,seven, eight, nine, ten or more release lines 526. Each release line 526is a burn wire. The release lines 526 will split into two or moreportions upon application of sufficient heat. The release lines 526 maybe formed from a variety of materials, including fabrics, metals,alloys, composites, fibers, nichrome, other suitable materials, orcombinations thereof. The size of the release lines 526, for examplethickness, may be chosen based on a variety of parameters, includingmass of the LTA system 100 or portions thereof, the amount of heat to beapplied to the release lines 526, environmental conditions during flightand upon actuation of the release mechanism 503, etc.

The release lines 526 couple together upper and lower portions of thegimbal 501. As shown, the release lines 526 couple together the upperbracket 530 and the second gear 520. The release lines 526 may coupletogether other portions of the gimbal 501. In some embodiments, therelease lines 526 may couple together other portions of the LTA system100, such as portions of the gimbal 501 and the ZPB 200 or SPB 300. Therelease lines 526 releasably couple together the various portions. Therelease lines 526 may thus provide for release or separation of thevarious portions of the LTA system 100 coupled together, for example byburning and separating of the release lines 526. As shown, the releaselines 526 provide for release of the upper portion of the gimbal 501,including among other things the upper bracket 530, from the lowerportion of the gimbal 501, including among other things the second gear520.

The release lines 526 may thus attach opposing portions of the gimbal501. The release lines 526 attach to the attachments 529 at the upperportion of the gimbal 501. The release lines 526 extend from these upperattachments downward to respective guides 528. The guides 528 areattached to the second gear 520. The guides 528 may be attached to otherstructures, such as an intermediate attachment between the second gear520 and the guides 528. The guides 528 are shown as U-bolts fixedlyattached to the second gear 520. The guides 528 define openings 531through the guides 528. The openings 531 are spaces of the guides 528through which the release lines 526 extend. The release lines 526 maywrap over and through the guides 528. The release lines 526 may wrapover the guides 528 once, as shown. In some embodiments, the releaselines 526 may wrap around the guides 528 one or more times beforeextending away from the guides 528. The guides 528 and openings 531thereof provide for a smooth, rounded surface over or around which therelease lines 526 wrap. The rounded portions of the guides 5289 may besized to reduce stress, wear, etc. on the release lines 526. The releaselines 526 extend from the guides 528 to opposing lower attachments 529of the gimbal 501. The lower attachments 529 are attached to the secondgear 520 opposite the respective guide 528. The release lines 526 arefixedly attached to the lower attachments 529. As shown, the releaselines 526 approach and exit the guides 528 at slightly more than aninety degree angle. The release lines 526 may be oriented in a varietyof other orientations. The release lines 526 extend from a respectiveguide 528 and over a separator assembly 534.

The release lines 526 may include burn portions 532 that extend over theseparator assembly 534. The burn portions 532 are portions of therelease lines 526 that separate upon application of heat from theseparator assembly 534. The burn portions 532 may be one or more regionsof the release lines 526. The burn portions 532 may include the materialthat separates upon application of heat. The entire release line 526 maybe made of the same material as the burn portion 532. In someembodiments, the burn portion 532 may be made of different material asthe remaining portions of the release line 526. For example, the burnportion 532 may include a burnable material while the remainder of therelease line 526 may not be burnable. The burn portion 532 may extendfrom a respective guide 528 to an opposing lower attachment 529. Theburn portion 532 may be a smaller portion that only is adjacent theseparator assembly 534.

A close up view of the separator assembly 534 is shown in FIG. 4D. Theseparator assembly 534 provides for separation of the release lines 526.The separator assembly 534 may separate the burn portions 532 of therelease lines 526 that extend from the guides 528 to opposing lowerattachments 529. The release lines 526 may extend over the separatorassembly 534 as shown. In some embodiments, the release lines 526 mayextend through, around, in, under, etc. the separator assembly 534.

The separator assembly 534 is mounted on a protrusion 536. Theprotrusion is part of the second gear 520. The protrusion 536 may be aseparate part from the second gear 520 that is attached to the secondgear 520. The protrusion 536 supports the separator assembly 534. Theseparator assembly 534 includes a nut castle 538. The nut castle 538 ismounted on the protrusion 536. The nut castle 538 may releasably attachto the protrusion 536. In some embodiments, the nut castle 538threadingly engages with, for example screws into, the protrusion 536and/or other portions of the second gear 520. The nut castle 538provides for securement of various features of the separator assembly534. The nut castle 538 may provide for extension therethrough ofvarious electrical wires, heating elements, burn mechanisms, etc. Theseparator assembly 534 may rotate with the SPB 300. For example, theseparator assembly may be attached to the SPB 300 such that rotation ofthe SPB 300 will rotate the separator assembly 534. The separatorassembly 534 may therefore rotate relative to the release lines 526.Rotation of the separator assembly 534 may distribute thermal energy,for example from a hot wire 544 as further described, over a widerportion of the burn portions 523 of the release lines 526.

The separator assembly 534 includes a hot wire plug 540. The hot wireplug 540 is secured by the nut castle 538. The hot wire plug 540 may bethreadingly engaged with the nut castle 540 or otherwise suitablysecured with the nut castle 538. The hot wire plug 540 is connected withan electrical current source, for example a battery, to provide electriccurrent to one or more hot wire engagements 542. The battery may belocal to the gimbal 501. In some embodiments, the battery may be locatedwith other portions of the LTA system 100, for example with the payloadsupport 700, and having wires extending from the payload support 700along the ladder assembly 610 and around or through the SPB 300. The hotwire engagements 542 couple with the hot wire plug 540. The hot wireengagements 542 when connected with the hot wire plug 540 are inelectrical communication with the electrical current source.

The hot wire engagements 542 are electrically connected to the hot wire544. The hot wire 544 thus receives electric current from the electriccurrent source. The hot wire 544 heats up upon receipt of electriccurrent therethrough. The hot wire 544 may be formed from a variety ofsuitable materials, such as metals, alloys, fibers, high electricalresistance materials, other suitable materials, or combinations thereof.The hot wire 544 may extend from a first hot wire engagement 542 to asecond hot wire engagement 542. Current may flow from the first hot wireengagement 542, through the hot wire 544 and to the second hot wireengagement 542. The hot wire 544 extends in a coil shape as shown. Insome embodiments, the hot wire 544 may have other shapes besides a coil.The hot wire 544 forms the coil between the hot wire engagements 542.The coil formed by the hot wire 544 may include multiple loops as shown.In some embodiments, the coil formed by the hot wire 544 may only be oneloop. The coil may be various sizes, for example various diameters andlengths, depending, for example, on the size of the burn portions 532 ofthe release lines 526, on the proximity of the hot wire 544 to the burnportions 532, on the amount of current applied to the hot wire 544, onthe amount of heat generated by the hot wire 544, etc. The coil formedby the hot wire 544 is shown as generally horizontal. In someembodiments, the coil formed by the hot wire 544 may be at otherorientations, for example angled, vertical, etc. In some embodiments,there may be multiple coils formed by the hot wire 544.

The hot wire 544 heats up and transfers heat to the release lines 526.The hot wire 544 transfers heat to adjacent and/or contacting portionsof the release lines 526. The hot wire 544 transfers heat to the burnportions 532 of the release lines 532. The transferred heat causes theburn portions 532 to burn and thereby separate. The burn portions 532may be positioned adjacent to the hot wire 544. As shown, the burnportions 532 extend over the hot wire 544. The burn portions 532 mayextend through, around, under, etc., the hot wire 544. In someembodiments, the burn portions 532 may extend through the coil formed bythe hot wire 544. In some embodiments, the burn portions 532 maypartially extend adjacent to the hot wire 544 and partially extendthrough the coil formed by the hot wire 544. In some embodiments, theburn portions 532 may contact the hot wire 544. The hot wire 544includes a single burn region, e.g. the coil, that causes multiple burnportions 532 of the release lines 526 to separate. In some embodiments,there may be multiple burn regions, for example multiple coils, thatcause multiple burn portions 532 of the release lines 526 to separate.Thus, the configuration shown is merely one example and many othersuitable configurations may be implemented.

The separator assembly 534 or portions thereof may rotate with the SPB300. Rotation of the separator assembly 534 may distribute thermalenergy over a wider part of the burn portions 532. For example, the burnportions 532 may extend over the coiled hot wire 544 and rotation of thehot wire 544 relative to the burn portions 532 will cause thermalcommunication with multiple sections of the burn portions 532 as the hotwire 544 rotates underneath those sections. The hot wire 544 may rotaterelative to the burn portions 532 because the burn portions 532 arecoupled with the upper portion of the gimbal 500 that can rotaterelative to the bottom portion of the gimbal 500 that includes theseparator assembly 534. The separator assembly 534 may be connected tothe SPB 300 via a shaft or other member so that rotation of the SPB 300relative to the ZPB 200 also rotates the separator assembly 534 relativeto the ZPB 200.

The release assembly 534 thus includes a “burn” type release mechanism.In some embodiments, other release mechanisms may be implemented. Inaddition or alternatively to the burn type release mechanism, therelease assembly 534 may include, for example, cutters that cut therelease lines 526, separation nut mechanisms that separate portions of anut in a nut and bolt assembly, actuated release members that actuateupon command to release the release lines 526, etc. Thus, the particularconfiguration for the release assembly 534 described in detail herein ismerely one example, and many other types of release assemblies 534 maybe implemented with the LTA system 100.

The actuation of the release assembly 534 causes separation of the ZPB200 and the SPB 300. In addition, actuation of the release assembly 534may also cause termination of the flight of the ZPB 200 and/or SPB 300.In some embodiments, termination of the flight of the ZPB 200 isinitiated by “goring.” Goring refers to at least partial removal of atleast one of the gores 925 of the ZPB 200. One or more of the gores 925may be torn from the remaining portions of the skin 220 of the ZPB 200.The gores 925 may be torn from the upper portion 210, for example fromthe top 212, of the ZPB 200.

The gimbal 501 includes the tear line 535. There may be multiple tearlines 535. In some embodiments, the gimbal 501 may not include any tearline 535. The tear line 535 of the gimbal 501 may be similar to the tearline 535 as described above with respect to the gimbal 500. The tearingof gores 925 may be accomplished by the tear line 335. The tear line 535is able to remain attached to the gimbal 501 after actuation of therelease assembly 534. Actuation of the release assembly 534 causes theSPB 300 and portions of the gimbal 501 attached thereto to fall awayfrom ZPB 200. A lower end of the tear line 535 is attached to a lowerportion of the gimbal 501, e.g. to the attachment 529 as shown. An upperend of the tear line 535 on an opposite end may be attached to one ormore of the gores 925 of the ZPB 200 at various locations, for exampleat or near the upper portion 210 of the ZPB 200. The upper end of thetear line 535 may be connected to seams between adjacent gores 225, totape between the gores 925, to the upper ends of the gores 925, to skin220 portions of the gores 925, to other locations, or combinationsthereof. When the SPB 300 with a portion of the gimbal 501 falls awayfrom the ZPB 200, the tear line 535 tears out the corresponding one ormore gores 925 from the ZPB 200, causing destruction of the ZPB 200 andterminating the flight.

In some embodiments, in addition or alternatively to connection with thegimbal 501, the lower end of the one or more tear lines 535 may extendand connect to other components of the LTA system 100. In someembodiments, the tear line 535 may extend from the gores 925 to the SPB300. For example, the release assembly 534 may cause the SPB 300 toseparate from the ZPB 200, and the weight of the now-separated SPB 300may pull on the tear lines, causing the gores 925 to rip away from theZPB 200. In some embodiments, the tear lines extend from the gores 925to the stratocraft 400. For example, the release assembly 534 may causethe SPB 300 to separate from the ZPB 200, and the weight of thenow-separated stratocraft 400 may pull on the tear line 535, causing thegores 225 to rip away from the ZPB 200. By causing the gores 925 to ripaway from the remaining portions of the skin 220 of the ZPB 200, thelift gas inside the ZPB 200 is allowed to escape. The decrease in liftgas causes the ZPB 200 to lose lift, and the weight of the ZPB 200 causea net downward force on the ZPB 200, causing the ZPB 200 to fall to theground.

Various embodiments of the gimbal 501 may include all electricalconnections, wires, controls, etc. routed to and from only the SPB 300side of the gimbal 501. This may allow electrical power and control tocome from the payload support 700 or components thereof. It is also asignificant mass and complexity benefit not to have electricalconnections and wiring routed from both the top and the bottom sides ofthe gimbal 501. For example, with the gimbal 501 electrically connectedon only the SPB 300 side, actuation of the release assembly 534 wouldnot require an electrical disconnect from the ZPB 200 side of the gimbal501, and it would reduce or eliminate the need for any electricalcomponents associated with the gimbal 501 to be in or on the ZPB 200. Insome embodiments, this one-sided arrangement could be reversed such thatall electrical power and control signals, etc. are routed to the ZPB 200side of the gimbal 501. In some embodiments, the various one-sideelectrical configurations may be implemented with the gimbal 500.

The various embodiments of the gimbal, including the gimbal 500 and 501,and the various components thereof, may be electronically controlled. Asfurther described herein, a control system 1000 may electronicallycontrol the gimbal 500 and the various components thereof.

E. Stratocraft

FIGS. 5A and 5B are, respectively, perspective and side views of anembodiment of the stratocraft 400. The stratocraft 400 includes variousfeatures for supporting mission objectives of the system 100, such as apayload and supporting subsystems. The stratocraft 400 includesembodiments of an upper craft 600 and a payload support 700. The uppercraft 600 is coupled with the SPB 300. The upper craft 600 may becoupled with the bottom 317 of the SPB 300. The upper craft 600 may berigidly coupled with the SPB 300. In some embodiments, the connectionbetween the upper craft 600 and the SPB 300 may have the same or similarfeatures and/or functionalities as the various connections between theSPB 300 and the ZPB 200.

The upper craft 600 includes a ladder assembly 610. The ladder assembly610 is an elongated, structural connector that couples the payloadsupport 700 with the SPB 300. The ladder assembly 610 may coupledirectly or indirectly with the SPB 300. The ladder assembly 610 maycouple the payload support 700 with the SPB 300 such that the payloadsupport 700 is located below the SPB 300 when the LTA system 100 is inflight. The ladder assembly 610 may be coupled with the SPB 300 suchthat rotation of the SPB 300 will rotate the ladder assembly 610. Theladder assembly 610 may couple with and/or support other features, asdescribed herein. The ladder assembly 610 includes one or more wires forstructurally supporting the payload support 700, as described in furtherdetail herein, for example with respect to FIG. 5C. The ladder assembly610 also includes an air hose 690, which is a conduit fluidly connectingthe SPB 300 with the compressor assembly 800. In some embodiments, theladder assembly 610 and the air hose 690 are the same components,although they may be separate components, as described herein. Theladder assembly 610 may have a length based at least in part on avoidingshading from the LTA system 100 during daylight, for example in order toprovide sunlight to a solar array 630. Such shading may be due to theSPB 300 and/or ZPB 200 located above the stratocraft 400.

The stratocraft 400 includes the solar array 630. The solar array 630may be part of the upper craft 600, as shown. The solar array 630includes one or more solar panels configured to receive sunlight forconversion to electrical energy. The solar array 630 is generallyplanar. In some embodiments, the solar array 630 may be curved orotherwise flexible. A variety of suitable solar array 630 types may beused, including solar panels with cell efficiencies of about 23%, lowcost per watt, without light-induced degradation, a low temperaturecoefficient, and/or having low light and broad spectral response. Solarpanels of the solar array 630 also include features to address largetemperature variations due to the very hot and very cold extremes of thehigh altitude environment

The solar array 630 is coupled with the ladder assembly 610. The one ormore solar panels of the solar array 630 may be located along the lengthof the ladder assembly 610. The solar array 630 may be directly orindirectly coupled with the ladder assembly 610. The solar array 630 iscoupled with the ladder assembly 610 such that rotation of the ladderassembly 610 will rotate the solar array 630. The solar array 630 may berotated to point at the sun for maximum solar energy conversion, asdescribed herein. The solar array 630 rotates about the longitudinalaxis 105 for azimuth adjustments. In some embodiments, the solar array630 may rotate about multiple axes, for example, for azimuth andelevation adjustments.

The stratocraft 400 includes a bag 640. The bag 640 may be part of theupper craft 600. The bag 640 is used to contain features of a parafoil680, as described herein. The bag 640 may be a parachute bag or similarreceptacle for containing the parafoil 680 features and allowing releasetherefrom. The bag 640 may be formed from a variety of materials,including fabric, other materials, or combinations thereof. The bag 640is coupled with the ladder assembly 610. As shown, the bag 640 isconnected to the ladder assembly 610 by a cord 642. The bag 640 may bedirectly attached to the ladder assembly 610. In some embodiments, thebag 640 may be releasably coupled with the ladder assembly 610.

The stratocraft 400 includes a cover 650. The cover 650 may be part ofthe upper craft 600. The cover 650 is used to contain features of aparafoil 680, as described herein. The cover 650 may be an elongatedtube-like fabric for containing the parafoil 680 features and allowingrelease therefrom. The cover 650 may be formed from a variety ofmaterials, including fabric, other materials, or combinations thereof.The cover 650 is coupled with the bag 640. The cover 650 may be directlyattached to the bag 640. The cover 650 and bag 640 may be part of thesame, continuous sleeve for housing various portions of the parafoil680. For instance, the bag 640 may contain the bunched up canopy portionof the parafoil 680 while the cover 680 contains the lines of theparafoil. The cover 650 has an opening at the lower end for receivingthe parafoil 680 inside the cover 650.

The stratocraft 400 includes the parafoil 680. The parafoil 680 may bepart of the upper craft 600. The parafoil 680 is only partially shown inFIGS. 5A and 5B because it is stowed inside the cover 650 and bag 640.The parafoil 680 may be stowed during flight and then deploy to adeployed flight configuration, as described herein for example withrespect to FIG. 8. The parafoil 680 may be coupled with the ladderassembly 610, for example, via the cover 650 and bag 640.

The parafoil 680 provides a descent system for the payload support 700.The parafoil 680 is initially coupled with the payload support 700 andrestrained during flight. The parafoil 680 is then released from theupper craft 600, for example from the ladder assembly 610, the bag 640and/or the cover 650, at high altitude and controllably descends to alanding site on the ground with the payload support 700. Upon release,the parafoil 680 may slide out of the bag 640 and cover 650 and deployautomatically. Some example embodiments of parafoil technology that maybe used for the parafoil 680 are described, for example, in U.S. patentapplication Ser. No. 15/065,828, filed Mar. 9, 2016, titled RigidizedAssisted Opening System for High Altitude Parafoils, the entiredisclosure of which is incorporated herein by reference for allpurposes.

In some embodiments, the LTA system 100 includes a descent system inaddition or alternative to the parafoil 680. For instance, the LTAsystem 100 may, in addition or alternative to the parafoil 680, includeone or more parachutes, one or more drogue parachutes, otherdecelerators, or combinations thereof. The various descent systems mayhave some or all of the same or similar features and/or functionalitiesas described herein with respect to the parafoil 680. Thus, the variousdescent systems that may be incorporated in the LTA system 100 may haveone or more release mechanisms, etc. In some embodiments, the LTA system100 includes one or more of the descent systems described, for example,in U.S. patent application Ser. No. 14/188,581, filed Feb. 24, 2014, andtitled NEAR-SPACE OPERATIONS, the entire disclosure of which isincorporated by reference herein for all purposes. In some embodiments,the LTA system 100 does not include any descent system.

The stratocraft 400 includes the air hose 690. The air hose 690 may bepart of the upper craft 600 and/or the payload support 700. The air hose690 is a hollow conduit providing for the movement of air therein. Aninner cavity thus extends along at least a portion of the ladderassembly 610 through the air hose 690. In some embodiments, the ladderassembly 610 is hollow from the upper end to the lower end. The air hose690 is formed from a generally flexible material, although in someembodiments it may be partially or entirely rigid. The air hose 690 maybe formed from a variety of suitable materials, including fabrics,fibers, metals, composites, other materials, or combinations thereof.The air hose 690 may be connected to the SPB 300, for example the bottom317, in a variety of suitable manners, including directly attached withfasteners, indirectly attached with brackets, etc. The air hose 690 maybe releasably coupled with the payload support 700, such that release ofthe payload support 700 from the upper craft 600 allows for release ofthe air hose 690 from the payload support 700.

The air hose 690 fluidly connects the SPB 300 with features for airintake and release at or near the payload support 700. Ambient air fromthe surrounding atmosphere may therefore be received at or near thepayload support 700 and transmitted via the air hose 690 to the SPB 300.The air hose 690 may be fluidly coupled with a compressor 810 asdescribed herein, where the compressor 810 is mounted with a payloadsupport 700 and the compressor 810 is fluidly coupled with the interiorvolume of the SPB 300 via the air hose 690. Air from inside the SPB 300may be released through the air hose 690 back to the surroundingatmosphere.

FIG. 5C is a close up view of a portion of the ladder assembly 610. Theladder assembly 610 includes one or more rungs 612. There are two rungs612 visible in the figure. The ladder assembly 610 may include five,ten, twenty, thirty, fifty, one hundred, or other lesser, in between orgreater amounts of rungs 612. The rungs 612 are structural supportslocated along the length of the ladder assembly 610. The rungs 612 maybe generally evenly spaced along the length of the ladder assembly 610from the payload support 700 to the SPB 300.

The rungs 612 include a body 613. The body 613 may be formed from avariety of suitable materials, including metals, composites, plastics,other suitable materials, or combinations thereof. The body 613 may bepartially or entirely rigid, or partially or entirely flexible. The body613 forms a generally triangular shape. In some embodiments, the body613 may form a variety of shapes, including rounded, circular, square,rectangular, other polygonal shapes, other suitable shapes, orcombinations thereof. The body 613 is generally flat.

The body 613 of each rung 612 forms an opening 614 generally though thecenter of the rung 612, The opening 614 is configured, for examplesized, to receive therein the air hose 690. The air hose 690 extendsthrough the series of rungs 612 through the openings 614. The openings614 may be sized to provide for an interference fit with the air hose690. The openings 614 may be sized to provide for a loose with the airhose 690. air hose 690 extends along the length of the ladder assembly610. The ladder assembly 610 may at least partially support the air hose690, for example via the rungs 612. In some embodiments, the air hose690 is supported at various locations along the ladder assembly 610 bythe rungs 612. In some embodiments, the air hose 690 may extendpartially or completely along the outside of the ladder assembly 610.

The rungs 612 include one or more guide openings 616. As shown, eachrung 612 includes three guide openings 616. The guide openings 616 arelocated at or near the edges of the body 613. As shown, the guideopenings 616 are located at the vertices of the triangular-shaped rungs612. The guide openings 616 define spaces configured to receive thereina ladder rope 620.

The ladder assembly 610 includes one or more ladder ropes 620. As shownin FIG. 5C, the ladder assembly 610 includes three ladder ropes 620. Insome embodiments, the ladder assembly 610 may include less than or morethan three ladder ropes 620. The ladder ropes 620 are structuralconnectors that connect the payload support 700 with the SPB 300. Theladder ropes 620 may be formed from a variety of suitable materials,including composites, fibers, metals, plastics, other suitablematerials, or combinations thereof. The ladder ropes 620 may secure therungs 612 in place. For example, clips, knots, or other features of theladder ropes 620 may be incorporated at desired spacings to secure therungs 612 at corresponding desired spacings. The ladder ropes 620 may bereleasably connected with the payload support 700, as described herein.The ladder ropes 620 may couple with the SPB 300 directly or indirectly,for example via structural connectors located at the bottom 317 of theSPB 300, or otherwise with the lower portion of the SPB 300. In someembodiments, the ladder ropes 620 may extend all the way to the ZPB 200,for example for connection to the top of the gores 925 for goring theZPB 200 upon flight termination, as described herein.

The rungs 612 may couple other features with the ladder assembly 610.The rungs 612 may connect the solar array 630, the cord 642, the bag640, the cover 650, the parafoil 680, and/or other features with theladder assembly 610.

F. Payload Support

FIG. 6 is a top perspective view of an embodiment of the payload support700. The payload support 700 provides structural support to a payload730 and other subsystems. The payload 730 may be a variety of differentsystems, including but not limited to instruments and passenger spacecapsules, as further described herein. Thus, while the particularembodiment shown is related to a particular payload 730 and payloadsupport 700 with particular configurations, the disclosure is notlimited to only these features and configurations. A variety of otherpayloads and support structures and configurations may be used with thesystem 100. For reference, a direction P is indicated. The direction Pis a geometric reference direction that is “fixed” to the payloadsupport 700 frame of reference, such that the direction P points indifferent directions as the payload support 700 rotates.

The payload support 700 includes a frame 710. The frame 710 is a rigidstructure providing support and stability to various features of thesystem 100. The frame 100 may be formed from a variety of suitablematerials, including metals, composites, other materials, orcombinations thereof. The frame 710 may have a variety ofconfigurations. As shown, the frame 710 is in the shape of atetrahedron. The frame 710 thus has three side faces 711, 712, 713. Onlyside faces 711 and 712 are visible in FIG. 6, with side face 713 locatedon the backside of the payload support 700 as oriented in the figure. Alower face 714 is located on the lower end of the payload support 700and partially in between the three side faces 711, 712, 713. The lowerface 714 may be entirely or substantially open. The lower face 714 mayinclude the payload 730, as described herein. The faces 711, 712, 713may be planar as shown, or have other contours, and be located generallyin between side members of the frame 710. The tetrahedral frame 710forms an apex at the intersection of the frame 710 members that pointsin the direction P, which is away from the lower face 714. As shown, thedirection P may align with the +Z direction. In some embodiments, thedirection P may not align with the +Z direction.

The payload support 700 is releasably coupled with the upper craft 600.The payload support 700 is attached during flight to the upper craft600, such as to the ladder ropes 620. The payload support 700 is thenreleased for descent back to ground with the parafoil 680 and payload730.

The payload support 700 is coupled with the upper craft 600 via aflaring bracket 715, parafoil lines 682, and release lines 719. Upperends of the release lines 719 are attached to the upper craft 600 andlower ends of the release lines 719 are releasably attached to thepayload support 700. Upon release of the lower ends of the release lines719 from the payload support 700, an increased downward force is thenapplied to the flaring bracket 715, due to the loss of support from therelease lines 719, ultimately causing the flaring bracket 715 toseparate from the payload support 700 and re-orient the payload support700.

In some embodiments, the increased force due to release of the releaselines 719 causes the payload support 700 along with the attachedparafoil 680 to fall from the upper craft 600. The parafoil 680 thusslides out of the cover 650 and bag 640. After the parafoil 680 exitsthe cover 650 and bag 640, the parafoil 680 deploys into flightconfiguration. Upon deploying into flight configuration, a force due todeceleration is transmitted to the flaring bracket 715. The flaringbracket 715 is held down by a cord that breaks at a threshold force. Theforce due to deceleration exceeds this threshold force and breaks thecord, causing the flaring bracket 715 to separate from the payloadsupport 700. The detachment or separation of the flaring bracket 715thus causes the payload support 700 to re-orient, as described below.

In some embodiments, the increased force due to release of the releaselines 719 alone causes the flaring bracket 715 to release. In this case,the flaring bracket 715 has separated before the payload support 700 hassignificantly fallen from the upper craft 600 and before the parafoil682 has slid out of the cover 650. The flaring bracket 715 thusseparates from the frame 710 as the payload support 700 falls away fromthe upper craft 600. As the payload support 700 falls away, the parafoil680, which is attached to the payload support 700 via the parafoil lines682, is pulled out of the cover 650 and bag 640. After the parafoil 680exits the cover 650 and bag 640, the parafoil 680 deploys into flightconfiguration. Further, the parafoil lines 682 are attached at locationsof the payload support 700 such that the payload support 700 re-orientsupon release of the flaring bracket 715, as described below.

Lower ends of the parafoil lines 682 are connected at locations of theframe 710 such that the payload support 700 re-orients, e.g. rotates,upon release from the upper craft 600. In some embodiments, the parafoillines 682 are connected with the lower face 714, such as with asupporting bracket of the lower face 714. As shown, the flaring bracket715 is coupled with lines 682 of the parafoil 680. The release lines 719also releasably couple the payload support 700 with the upper craft 600.As shown, three release lines 719 extend through a guide 717 and upalong the ladder assembly 610. The release lines 719 may be releasedfrom the payload support 700.

The payload support 700 includes landing pads 721, 722, 723. The landingpads 721, 722, 723 are structural absorbers configured to absorb impactupon landing. As shown, there are three landing pads 721, 722, 723located in corners of the first side face 712. In some embodiments,there may be less than or greater than three landing pads and/or in avariety of locations. The landing pads 721, 722, 723 may be crushablestructures that collapse upon landing to attenuate forces due tolanding, for example to protect the payload and other systems. Thepayload support 700 also includes bumpers 726, 727 on a frame 710 memberlocated opposite the side face 712 and the landing pads 721, 722, 723.The bumpers 726, 727 provide extra protection for the frame 710, forexample in the event of rollover upon landing.

The payload support 700 includes the payload 730. The payload 730 iscoupled with the payload support 700, for example structurally attached.The payload 730 may be coupled with the payload support 700 so that itis dynamically and/or vibrationally isolated from the payload support700 to attenuate force transmission from the payload support 700 to thepayload 730. The payload 730 is located generally at or near the lowerface 714 of the payload support 700. The payload 730 may therefore befacing toward ground while the system 100 is in flight. The payload 730may be considered “nadir-pointing,” for example the payload 730 may havea field of view that points generally toward the ground. The payload 730may be or have a variety of suitable systems, sensors, computingcapabilities, etc. In some embodiments, the payload 730 is aninstrument, for example an optical instrument. In some embodiments, thepayload 730 is a sensor or sensor suite, for example infrared, visual orthermal sensors. The payload 730 may be other types of systems, orcombinations thereof. The payload 730 may weigh about 200 pounds.Depending on the embodiments, the payload 730 may be within a range ofweights from about 30 pounds or less to about 500 pounds or more.

The LTA system 100 includes one or more sensors 740. As shown, thepayload support 700 includes one or more sensors 740. The sensors 740are coupled with the frame 710. The sensors 740 may be in a variety ofdifferent locations of the payload support 700. The sensors 740 may belocated or otherwise associated with the payload 730, a compressorassembly 800, and/or other subsystems or components of the payloadsupport 700.

The sensors 740 are devices for detecting various parameters andproviding a corresponding output indicative of those parameters. Thesensors 740 may be coupled with the LTA system 100 and configured todetect an environmental parameter or attribute. The parameters detectedmay be related to various events, changes, properties, etc. Suchparameters may be related to the LTA system 100 or components thereof,and/or to the surrounding environment (e.g. atmosphere). The sensors 740may be a variety of different types of sensors. The sensors 740 may bepressure sensors (such as transducers) for detecting the ambientpressure, which may be used for, among other things, determiningaltitude. The sensors 740 may be temperature sensors for detectingambient temperature, which may be used for among other things,determining air flow rates or intended pressures for the SPB 300. Thesensors 740 may be accelerometers and/or gyroscopes, which may be usedfor among other things determining position, velocity and accelerationof the LTA system 100 or various components thereof. The sensors 740 maybe sun sensors, which may be used for among other things pointing thesolar array 630 toward the sun. These are just some examples, and thesensors 740 may be many other different types of sensors and based onmany other sensing principles, including light sensors, infraredsensors, thermocouples, potentiometers, magnetic field sensors,gravitational sensors, humidity sensors, moisture sensors, vibrationsensors, electrical field sensors, sound sensors, forces sensors, straingages, piezoelectric sensors, resistive sensors,micro-electro-mechanical sensors (MEMS), ultrasonic sensors, humiditysensors, gas sensors, chemical sensors, flow sensors, other sensors, orcombinations thereof.

Besides the payload support 700, the sensors 740 may in addition oralternatively be included with various other components of the LTAsystem 100, for example with the ZPB 200, the SPB 300, the gimbal 500,the upper craft 600, the solar array 630, the parafoil 680, the payload730, the various release mechanisms, other features of the system 100,or combinations thereof. In some embodiments, one or more sensors 740are located or otherwise associated with the ZPB 200 and/or the SPB 300.For example, the ZPB 200 and/or the SPB 300 may include pressure sensorsfor detecting internal pressures, flow sensors for detecting the flow ofair into and/or out of the balloons, temperature sensors for detectingthe temperature inside and/or outside of the balloons or of the balloonmaterials, accelerometers and/or gyroscopes for detecting theacceleration and/or velocity of the balloons, position sensors fordetecting the positions of the balloons or of various components orportions of the balloons, etc.

The payload support 700 includes a compressor assembly 800. Thecompressor assembly 800 is coupled with the payload support 700. Thecompressor assembly 800 is shown mounted within the payload support 700.The compressor assembly 800 may be coupled with the payload support in avariety of suitable ways, including indirectly attached via brackets orother structures, directly attached to the frame 710, other suitableattachment means, or combinations thereof. The compressor assembly 800provides for moving ambient air from the surrounding atmosphere into theSPB 300, and for moving air contained inside the SPB 300 back to thesurrounding atmosphere, as described herein. The compressor assembly 800is therefore fluidly coupled with ambient air in the surroundingatmosphere and fluidly coupled with the interior of the SPB 300. Thecompressor assembly 800 is coupled with the SPB 300 via the air hose690. As shown, the air hose 690 extends upward from the compressorassembly 800 and through the ladder assembly 610. This is merely one ofa number of suitable configurations. For instance, the air hose 690 mayextend in different directions from the compressor assembly 800, mayextend along the outside of the ladder assembly 610, etc.

G. Compressor and Valve

FIGS. 7A and 7B are perspective views of the compressor assembly 800.

For clarity, the compressor assembly 800 in FIGS. 7A and 7B is shown inisolation from other features of the LTA system 100. The air hose 690and payload support 700, among other features, are therefore not shownin FIGS. 7A and 7B. FIG. 7A shows a first side perspective view of thecompressor assembly 800, and FIG. 7B shows an opposite side perspectiveview of the compressor assembly 800.

The compressor assembly 800 causes ambient air from the surroundingatmosphere to enter the compressor assembly 800. The ambient airentering the compressor assembly 800 flows into the compressor assembly800 generally in the direction 801. Air inside the compressor assembly800 can flow out of the compressor assembly 800 and generally in thedirection 802. The air flowing out of the compressor assembly 800 in thedirection 802 flows toward the SPB 300 to provide more air inside theSPB 300. Air from inside the SPB 300 can flow back into the compressorassembly 800 in the general direction 803 to provide less air inside theSPB 300. Air from inside the compressor assembly 800 can also flow outof the compressor assembly 800 in the general direction 804 and/or 805.The air flowing out of the compressor assembly 800 in the directions 804and 805 flows back into the surrounding atmosphere, for example to ventair from the SPB 300. The compressor assembly 800 is controllable tocause the air to flow in the directions 801, 802, 803, 804, 805 asdescribed herein. It is understood that the directions 801, 802, 803,804, 805 are illustrative only, and that the air may flow alongdifferent flow lines that are still generally in the directions 801,802, 803, 804, 805.

The compressor assembly 800 includes a compressor 810. The compressor810 causes ambient air from the surrounding atmosphere to enter thecompressor assembly 800. The compressor 810 is in fluid communicationwith the ambient air and with the interior volume of the SPB 300 and isconfigured to compress the ambient air and pump the compressed air intothe interior volume of the SPB 300 to increase the downward force to theLTA system 100. The increased downward force to the LTA system 100 isdue to compressing the air internal to the SPB 300, thus making thecompressed air density greater than the surrounding ambient air.

The compressor 810 is a mechanical device that increases the pressure ofthe air taken in from the surrounding atmosphere and transports ittoward the SPB 300. The particular compressor 810 type may depend on theparticular mission. For higher altitude and/or heavy payload liftingmissions, the compressor 810 is a centrifugal compressor, that mayinclude an inlet, impeller, diffuser, and collector.

The centrifugal version of the compressor 810 uses a rotating impellerto force the ambient air to the impeller, thus increasing the velocityof the gas. The diffuser then converts the velocity energy to pressureenergy. The centrifugal version of the compressor 810 may includemultiple stages. In some embodiments, the compressor 810 is a two stage,centrifugal compressor, which is improved or optimal for higher pressureratios at high altitude and/or for heavy payload lifting missions. Thetwo stage, centrifugal version of the compressor 810 may produce about4000 watts (W) or about 6 horsepower (hp), have a compression ratio ofgreater than about 3:1, and/or achieve differential pressures of about0.5 pounds per square inch (PSI). In some embodiments, the centrifugalversion of the compressor 810 comprises two or more stages, and isconfigured to provide at least 500 liters of the ambient air per secondto the interior volume of the SPB at altitudes above 50,000 feet, aboveabout 70,000 feet, and/or other high altitudes. The centrifugalcompressor may be configured to provide the ambient air to the interiorvolume of the SPB 300 such that a resulting descent rate of the LTAsystem 100 is at least 10,000 feet per hour at altitudes above about50,000 feet, above about 70,000 feet, and/or other high altitudes. Theresulting descent rate of the LTA system 100 may be at least 20,000 feetper hour at altitudes above about 50,000 feet, above about 70,000 feet,and/or other high altitudes. The compressor 810 may provide a flow rateof about 500 liters per second (lps) at altitudes above about 50,000feet, above about 70,000 feet, and/or other high altitudes. Depending onthe embodiment, the compressor 810 may provide a flow rate within arange of flow rates from about 350 lps or less to about 1000 lps or moreat altitudes above about 50,000 feet, above about 70,000 feet, and/orother high altitudes.

The compressor assembly 800 includes an air intake 812. The air intake812 provides a structural feature through which the ambient air in thesurrounding atmosphere enters the compressor assembly 800. The airintake 812 is designed to provide for high flow rate of air, dependingon the required air intake of the LTA system 100. The air intake 812defines an opening 813. The air entering the air intake 812 flowsthrough the opening 813, in the general direction 801. The air enteringthe opening 813 of the air intake 812 may flow from an envelope 814. Asshown, the envelope 814 is conical. The conical shape of the envelop 814ensures laminar flow through the air intake 812 and to the impeller. Insome embodiments, the envelope 814 may have other shapes. The envelope814 is generally free of obstructions to allow for generallyunobstructed air flow into the opening 813 of the air intake 812. Asshown, the opening 813 is a circular space defined by the air intake812. In some embodiments, the opening 813 may have other suitableshapes. The opening 813 may be an open space largely free of otherstructures. In some embodiments, the opening 813 and/or air intake 812may include filters, vents, channels, other structures, or combinationsthereof.

The compressor assembly includes a volute 816 fluidly coupled with theopening 813. The volute 816 provides a conduit through which ambient airthat enters the opening 813 is transported to other locations. Thevolute 816 is a conduit through which the impeller of the compressor 810delivers the compressed air to the rest of the compressor assembly 800.The volute 816 may include the impeller therein.

The compressor assembly 800 includes a mount 820. The mount 820 supportsthe compressor assembly 800. The mount 820 is coupled with the payloadsupport 700. The mount 820 may be directly or indirectly attached to thepayload support 700. As shown, the compressor assembly 800 includesmultiple springs 822. The springs 822 couple the mount 820 with thepayload support 700, either directly or indirectly. The springs 822 areelastic structures, and may be coil springs, extension springs,compressive springs, other suitable springs, or combinations thereof.The mount 820 and springs 822 structurally (e.g. dynamically,vibrationally, etc.) isolate the compressor 810 from the payload support700, and vice versa. Vibrations and other movements of the compressorassembly 800, for instance due to the rotational velocity of theimpeller of the compressor 810, are attenuated so that such disturbancesare not entirely transmitted to the payload support 700. For example,vibrations due to operation of the compressor 810 are attenuated tomitigate or prevent disturbances from such vibrations affecting theoperation of the payload 730, such as an optical instrument. Thecompressor 810 is electrically connected to a speed controller via anelectrical connection 824. The electrical connection 824 is inelectrical communication with the control system 100 for control of thecompressor 810. The compressor assembly 800 also includes an outlet 826.The outlet 826 couples the volute 816 with a manifold 850. The outlet826 is configured to couple the volute 816 of the compressor 810 to theair manifold 850.

The compressor assembly 800 includes the manifold 850. The manifold 850is a structural channel providing for air flow through the manifold 850.The manifold 850 fluidly coupled various features of the compressorassembly 800. The manifold 850 is fluidly coupled with the compressor810 via the volute 816 and outlet 826. The manifold 850 is also fluidlycoupled with the SPB 300 and the surrounding atmosphere. The manifold850 thus provides for air movement between the compressor 810, the SPB300 and the surrounding atmosphere. For example, air may flow from thecompressor 810 and into the manifold 850 and then from the manifold 850and into the SPB 300. As further example, air may flow from the SPB 300and into the manifold 850 and then from the manifold 850 and into thesurrounding atmosphere. The air inside the manifold 850 may flow intothe surrounding atmosphere via a controlled valve 870 and/or emergencyvalve 871, as described herein. In some embodiments, the air inside themanifold 850 may flow into the surrounding atmosphere back through thecompressor 810. For example, the compressor 810 may allow for reversibleair flow. In some embodiments, the compressor 810 may passively allowfor reversible air flow. In some embodiments, the compressor 810 mayactively allow for reversible air flow, for example by actively causingair to exit the compressor 810, which may be out through the opening 813of the intake 812.

The compressor assembly 800 includes a hose coupling 852 having anopening 854. The hose coupling 852 may define the opening 854. The hosecoupling 852 provides for a fluid connection through the opening 854with the SPB 300, which may be via the air hose 690. The hose coupling852 may therefore couple with the air hose 690 to allow for air flowfrom the manifold 850, through the opening 854, through the air hose 690and into the SPB 300. The compressor 810 causes the air to enter themanifold 850 and flow through the air hose 690 to pressurize the SPB300.

The compressor assembly 800 includes the controllable valve 870, as bestseen in FIG. 7B. The valve 870 is a device for controllably allowing airflow from the compressor assembly 800. In some embodiments, thecompressor assembly 800 may include two valves: the controllable valve870 that is actively controllable to achieve the desired vent rate ofair from the SPB 300, and the emergency valve 871 being a passiveemergency pressure relief valve designed to prevent the SPB 300 frombeing over pressurized thus protecting the SPB 300.

The controllable valve 870 regulates, directs or controls the flow ofair by opening, closing, or partially obstructing various passageways.The air from inside the SPB 300 is fluidly connected to the manifold 850such that opening the valve 870 allows for air to flow from the SPB 300and into the surrounding atmosphere due to a higher pressure inside theSPB 300 relative to the surrounding atmosphere. In some embodiments, thevalve 870 is adjustable, in fluid communication with the ambient air andwith the interior volume of the SPB 300, and is configured to beadjusted to release the pumped-in ambient air from the interior volumeof the SPB 300 to the surrounding atmosphere to decrease the downwardforce to the LTA system 100. In some embodiments, the valve 870 isadjustable and is configured to be adjusted to release the pumped-inambient air from the interior volume of the SPB 300 to the surroundingatmosphere such that a resulting ascent rate of the LTA system 100 is atleast 10,000 feet per hour at altitudes above about 50,000 feet, aboveabout 70,000 feet, and/or other high altitudes. The resulting ascentrate of the balloon system may be at least 20,000 feet per hour ataltitudes above about 50,000 feet, above about 70,000 feet, and/or otherhigh altitudes.

As shown, the valve 870 includes a plate 875 that can be selectivelymoved to create an opening 877. The opening 877 is a passageway thatfluidly connects the manifold 850 with the surrounding atmosphere. Aircan thus flow from the manifold 850 and through the opening 877 into thesurrounding atmosphere. The air flow may be passive such that air willflow from the manifold 850 and into the surrounding atmosphere when thepressure of the air inside the manifold 850 is greater than the pressurein the surrounding atmosphere. In some embodiments, the valve 870 may bepassive, active or combinations thereof. The valve 870 may be one-way,such that air may only flow in one direction through the valve 870. Insome embodiments, the valve 870 may only allow for air flow from insidethe manifold 850 and into the surrounding atmosphere, which may be inthe general direction 805. The plate 875 can be moved to close the valve870 and thus seal the opening 877 to prevent air flow through the valve870.

The plate 875 is moved by an actuator 879 via a rod 880. The actuator879 can actuate, e.g. rotate, translate, preform other movements, orpreform combinations thereof, to move the rod 880 and thus the plate875. The actuator 879 is controllably actuated via electricalcommunication from the control system 1000 and/or from a ground stationor satellite. The actuator 879may cause the plate 875 to move bepredetermined amounts. The actuator 879 may cause the plate 875 to moveby various amounts to control the venting rate of air. In someembodiments, the valve 870 includes an air flow rate sensor such thatmovement of the plate 875 via the actuator is controlled based on adesired air flow rate. The actuator or portions thereof may be coupledwith and/or enclosed in a housing 882. The housing 882 is supported byfour supports 884. The supports 884 are connected to the manifold 850.

This is one of many suitable configurations of the valve 870, and othersuitable configurations may be implemented that allow for selectiveopening and closing of the valve 870. Further, the valve 870 may be orinclude a number of types of valves, components, other devices,structures, mechanisms, etc., for preventing and allowing air flow,including but not limited to vents, hydraulic valves, pneumatic valves,manual valves, solenoid valves, motors, bonnets, plugs, balls, ports,handles, actuators, discs, seats, stems, gaskets, springs, trims, orcombinations thereof. In some embodiments, there may be more than onecontrollable valve 870. In some embodiments, the valve 870 may be partof the compressor 810, for instance where the compressor 810 allows forair flow into the surrounding atmosphere.

The valve 870 allows for air to flow from the SPB 300 and into thesurrounding atmosphere. Air from the SPB 300 is in fluid connection withthe manifold 850 such that opening the valve causes air to flow from theSPB 300, through the manifold 850, and through the valve 870 into thesurrounding atmosphere. The rate of air flow out of the SPB 300 may becontrolled by controlling the valve 870. The control of the air flowrate though the valve 870 may be passive such that controllably openingthe valve 870 determines the air flow rate out of the SPB 300. Forexample, the valve 870 may be completely opened for maximum air flowrate out of the SPB 300. The valve 870 may be partially opened for lessthan maximum air flow rate out of the SPB 300. The valve 870 mayactively control air flow, for example with a fan, such thatcontrollably actuating the valve 870, for example controllably actuatingthe fan, actively controls the air flow rate out of the SPB 300.

The compressor assembly 800 includes the emergency valve 871. The valve871 is an emergency pressure relief valve for allowing air flow from thecompressor assembly 800, for example in the event of an overpressurization of the SPB 300. The valve 871 regulates, directs orcontrols the flow of air by opening, closing, or partially obstructingvarious passageways. In some embodiments, the valve 871 is adjustable,in fluid communication with the ambient air and with the interior volumeof the SPB 300, and is configured to be automatically adjusted torelease the pumped-in ambient air from the interior volume of the SPB300 if internal pressures are too high.

As shown, the valve 871 includes a plug 876 that can be selectivelymoved to create an opening 878. The opening 878 is a passageway thatfluidly connects the manifold 850 with the surrounding atmosphere. Aircan thus flow from the manifold 850 and through the opening 878 into thesurrounding atmosphere. The air flow may be passive such that air willflow from the manifold 850 and into the surrounding atmosphere when thepressure of the air inside the manifold 850 is greater than the pressurein the surrounding atmosphere. In some embodiments, the valve 871 may bepassive, active or combinations thereof. The valve 871 may be one-way,such that air may only flow in one direction through the valve 871. Insome embodiments, the valve 871 may only allow for air flow from insidethe manifold 850 and into the surrounding atmosphere, which may be inthe general direction 805. The plug 876 can be moved to close the valve871 and thus seal the opening 878 to prevent air flow through the valve871. This is one of many suitable configurations of the valve 871, andother suitable configurations may be implemented such as those describedwith respect to the controllable valve 870.

The valve 871 allows for air to flow from the SPB 300 and into thesurrounding atmosphere automatically when pressures inside the SPB 300are too high. Air from the SPB 300 is in fluid connection with themanifold 850 such that opening the valve causes air to flow from the SPB300, through the manifold 850, and through the valve 871 into thesurrounding atmosphere. The valve 871 may be in electrical communicationwith a sensor via the control system 100. For example, a sensor insidethe SPB 300 may detect an internal pressure of air inside the SPB 300and if this pressure satisfies a pressure threshold then the controlsystem 1000 may trigger the valve 871 to open. In some embodiments, insuch situations the controllable valve 870 may also be triggered toopen, for example where the vent rate of the emergency valve 871 isinadequate for a given internal pressure of the SPB 300. In someembodiments, the emergency valve 871 may be used in lieu of thecontrollable valve 870 for descent, for example where the controllablevalve 870 is malfunctioning or otherwise not providing the desireddescent rate. In some embodiments, the emergency valve 871 may be usedin addition to the controllable valve 870, for example where a fastervent and descent rate is desired than is obtainable with only thecontrollable valve 870. Further, there may be more than one emergencyvalve 871.

The payload support 700 may further include a variety of subsystems tosupport the mission. In some embodiments, the payload support 700 mayinclude communications, electrical, power, thermal, avionics, telemetry,guidance navigation and control (GNC), release, termination, and/orother subsystems, or combinations thereof.

The payload support 700 and the various components and subsystemsthereof may be electronically controlled. As further described herein,the control system 1000 may electronically control the payload support700 and the various components thereof, such as the compressor assembly800, the payload 730, the parafoil 680, the various release mechanisms,the various subsystems, etc. The control system 1000 may electronicallycontrol the compressor assembly 800 and the various components thereof.As further described herein, in some embodiments, the compressor 810 iscontrolled for controllably providing air to the SPB 300, for example todescend in altitude or to maintain an altitude. In some embodiments, thecompressor 810 is controlled for controllably releasing air from the SPB300, for example to ascend in altitude or to maintain an altitude.

H. Descent System

FIG. 8 is a perspective view of the parafoil 680. The parafoil 680 isshown separated from the LTA system 100 and in a deployed flightconfiguration with the payload support 700. As described herein, theparafoil 680 separates from the upper craft 600 and deploys in theflight configuration to descend to ground with the payload support 700.In some embodiments, the parafoil 680 may be configured to deploy intothe flight configuration before separating from the rest of the LTAsystem 100. Thus, the descriptions of particular configurations of theparafoil 680, and of particular deployment and flight procedures of theparafoil 680, are not meant to limit the scope of the LTA system 100 andrelated methods to only those particular configurations and procedures.

The parafoil 680 includes a canopy 684. The canopy 684 is shown in thedeployed, flight configuration. The canopy 684 is at least partially asoft structure that provides lift to the parafoil 680. The canopy 684may have more rigid features, such as stiffeners, local attachments,etc. The deployed canopy 684 is generally shaped like a bent wing, witha cross-sectional geometry approximating an airfoil shape. The canopy684 may have openings allowing for air to flow through and into thecanopy 684. Such air flow may assist with achieving and/or maintainingthe deployed shape of the canopy 684. The canopy 684 is capable of beingstowed in a collapsed configuration and of deploying into the flightconfiguration. The stowed canopy 684 is stored within the bag 640 and/orwithin the cover 650 of the stratocraft 400. As discussed, the parafoil680 may be released from the upper craft 600, for example from the bag640 and/or cover 650. The canopy 684 may be released from the bag 640and/or cover 650 upon deployment of the parafoil 680.

The parafoil 680 includes one or more lines 682. The lines 682 couplethe canopy 684 with the payload support 700. As shown, there aremultiple lines 682 attaching the canopy 684 to the flaring bracket 715of the payload support 700. The flaring bracket 715 is shown in adetached configuration, where the flaring bracket 715 has detached fromthe payload support 700. The lines 682 may couple the flaring bracket715 to various locations of the canopy 684, including the front, back,center, one or more sides, other locations, or combinations thereof, ofthe canopy 684. The lines 682 transmit a lifting force from the canopy684 to the payload support 700. The lines 682 may be formed of a varietyof suitable materials, including fiber, composite, metallic, othermaterials, or combinations thereof.

The lines 682 may be rigid or rigidized to assist with the deploymentprocess of the parafoil 680. The lines 682 may extend through a rigidsleeve such as a composite tube, or have a rigid rod inserted into themin order to prevent entanglement during deployment and to assist in theopening of the canopy 684 at high altitudes where air densities are low.In some embodiments, some or all of the lines 682 may be rigidized. Forexample, some of the lines 682 may include relatively stiffer coversaround the lines. Such stiff covers of the lines 682 may assist withdeployment of the lines 682 and/or with mitigating or preventingentanglement of the lines 682. In some embodiments, the parafoil 680includes one or more rigidized assist opening members. For example, theparafoil 680 may include flexible rods that connect the payload support700 to the canopy 684. The flexible rods may store potential energy in aflexed, stowed state and use that energy to assist with releasing anddeploying the canopy 684 into flight configuration. Such flexible rodsmay be in addition or alternatively to the stiffened lines 682. Theseare merely some examples of the multitude of configurations for parafoil680. Further details of some of these and other configurations for theparafoil 680 are described, for example, in U.S. patent application Ser.No. 15/065,828, filed Mar. 9, 2016, titled Rigidized Assisted OpeningSystem for High Altitude Parafoils, the entire disclosure of which isincorporated herein by reference for all purposes.

The parafoil 680 is shown in flight attached to the payload support 700.As mentioned, the LTA system 100 may re-orient the payload support 700in flight relative to its orientation when coupled with the upper craft600. The payload support 700 is thus shown in FIG. 8 re-orientedrelative to the orientation shown in FIG. 6. In particular, in FIG. 8the direction P is now at an angle with respect to the +Z direction. Thepayload support 700 has thus rotated about ninety degrees. The lowerface 714 is no longer facing in the −Z direction. The side face 712 isnow facing generally in the −Z direction. By not facing the lower face714 in the −Z direction, the payload 730 which is generally locatedalong the lower face 714 is further protected for landing. For instance,the payload support 700 will land on the −Z pointing side face 712 andnot on the side-facing lower face 714. Thus, the lower face 714 can beused to point the payload 730 toward ground during flight but thenrotate to land on a different face and protect the payload 730. Further,the landing pads 721, 722, 723 are now facing in the −Z direction andcan thus absorb most or all of the impact upon landing. In addition, thebumpers 726, 727 provide for further protection, for example if thepayload support 700 rolls over forward upon landing. The side face 713is on the back of the payload support 700 as oriented, and is thus notvisible. This is merely one example of the orientation that the payloadsupport 700 may assume after being re-oriented, and other orientationsmay be implemented.

The payload support 700 may re-orient using one or more line extensions750. The line extensions 750 are extensions of the parafoil lines 682.Some or all of the line extensions 750 may be separate lines coupledwith the flaring bracket 715 and/or with the parafoil lines 682. Some orall of the line extensions 750 and corresponding parafoil lines 682 maybe part of one, continuous line. The line extensions 750 are attached tothe payload support 700 in particular locations to cause the payloadsupport 700 to re-orient upon release from the upper craft 600. Asshown, the line extensions 750 are coupled with frame 710, for examplenear the bumper 727, and generally in the P direction. Other lineextensions 750 are coupled with the lower face 714, for example with thepayload 730 or other components. The flaring bracket 715 is locatedgenerally above the bumper 726.

I. Other LTA System Configurations

FIGS. 9A-9E depict alternate embodiments of the LTA system 100. FIGS. 9Aand 9B are side views of another embodiment of an LTA system 101. TheLTA system 101 may have some of the same or similar features and/orfunctionalities as the LTA system 100, and vice versa. The LTA system101 shown in FIG. 9A is at a different point in time than the LTA system101 shown in FIG. 9B.

The LTA system 101 is shown in flight. The LTA system 101 includes theZPB 200 coupled in tandem above the SPB 300. The LTA system 101 has anunderinflated ZPB 200 and SPB 300 in FIG. 9A relative to FIG. 9B. By“underinflated” it is meant the ZPB 200 and SPB 300 are not inflated ator near maximum capacity. The ZPB 200 and SPB 300 are inflated more inFIG. 9B relative to FIG. 9A. Thus, the ZPB 200 and SPB 300 arerelatively contracted in FIG. 9A and relatively expanded in FIG. 9B. TheLTA system 101 may have the configuration shown in FIG. 9A duringtakeoff or at relatively lower altitudes. The LTA system 101 may havethe configuration shown in FIG. 9B at relatively higher altitudes. Thus,the ZPB 200 and SPB 300 may expand as the LTA system 101 climbs inaltitude. For example, the ZPB 200 may expand as the LTA system 101reaches altitude with lower ambient air pressure, such that the LTA gasinside the ZPB 200 causes the ZPB 200 to expand. As further example, theSPB 300 may have insufficient air inside to pressurize it, such that theSPB 300 expands as more air flows into the SPB 300 and contracts as airis released from the SPB 300. As further example, the ZPB 200 may loseLTA gas at high altitudes where the ZPB 200 has reached maximum volumeand cannot expand any further but with rising temperatures causing theinside LTA gas to expand, thus causing trapped air and/or LTA gas toexit the ZPB 200, such as through one or more openings in the ZPB 200.These and other effects, or combinations thereof, may cause the varyingconfigurations (shapes, sizes, etc.) of the ZPB 200 and SPB 300.

The LTA system 101 includes the payload support 700 coupled below theSPB 300. The LTA system 101 does not include an elongated connection,such as the ladder assembly 610, between the payload support 700 and theSPB 300. Thus, in some embodiments, the payload support 700 may belocated closer to the SPB 30. The payload support 700 may be coupleddirectly underneath the SPB 300.

The LTA system 101 includes the compressor assembly 800. The compressorassembly 800 may be mounted with the payload support 700, as describedherein. Thus, the compressor assembly 800 may be located closer to theSPB 300. The compressor assembly 800 may be coupled directly underneaththe SPB 300. Further, the compressor assembly 800 need not be part ofthe payload support 700. In some embodiments, the compressor assembly800 may be separate from the payload support 700. In some embodiments,the compressor assembly 800 is directly coupled with the SPB 300 and avariety of different payload supports 700 may be separately incorporatedwith the LTA system 101. This may allow, for example, a modular LTAsystem 100 or 101 having the advanced maneuver and mission capabilitiesdescribed herein but that can also be used with a variety of differentpayloads and payload supports. For instance, the compressor assembly 800may be coupled directly underneath the SPB 300 and be configured for avariety of different payload supports to be coupled underneath thecompressor assembly 800. These are merely some examples, and othersuitable configurations may be implemented.

Other embodiments of the LTA system 100 besides those described hereinmay be implemented without departing from the scope of this disclosure.In some embodiments, the LTA system 100 may include instruments, thecompressor assembly 800, the parafoil 680, other descent systems besidesthe parafoil 680, additional payloads 730 and/or payload supports 700,an additional ballast hopper, and/or other systems, located above theSPB 300 and below the ZPB 200. Some exemplary configurations of suchsystems are described, for example, in U.S. provisional patentapplication No. 62/294,189, entitled VARIABLE ALTITUDE AIR BALLASTBALLOON SYSTEM and filed Feb. 11, 2016, the entire disclosure of whichis incorporated by reference herein for all purposes.

FIGS. 9C, 9D and 9E depict other embodiments of the LTA systems 100including, respectively, LTA systems 102, 103 and 104, having multipleSPB's 300 and/or a single SPB 300 having multiple, SPB-shaped internalair compartments or chambers. Thus, the description of “multiple SPB's”is not meant to exclude the configuration where there are multipleSPB-shaped compartments or chambers for a single SPB 300, thecompartments being the wide, balloon-shaped portions. By “SPB-shaped” itis meant that the shape is generally similar to that of the SPB 300described herein, for example with respect to FIGS. 3A and 3B, but neednot be the exact shape nor include all features thereof. FIG. 9C depictsan embodiment of an LTA system 102 having two SPB's 300. FIG. 9D depictsan embodiment of an LTA system 103 having three SPB's 300. FIG. 9Edepicts an embodiment of an LTA system 103 having four SPB's 300. Someembodiments of the LTA systems may have more than four SPB's 300.

To reach design goals, for example with the performance ratio Rdescribed above, as the balloon system gets larger, using only a singlepumpkin ballast balloon SPB 300 may not be desirable. For instance, forsome missions there may be a strength limitation or a stabilitylimitation with only a single SPB 300. An alternative is stacking theSPB's 300. This may not be as weight efficient as a single SPB 300, buta single SPB 300 may have structural or stability issues, such asS-clefting. Multiple smaller SPB's 300 may address these issues.Examples of LTA systems having two, three and four SPB's 300 are shownrespectively in FIGS. 9C, 9D and 9E.

A possible advantage of a second or third or fourth or more SPB 300, orof a single SPB 300 with multiple compartments, in the system is themaximum diameter and thus volume of the SPB 300 is constrained by thehoop stress of the material it is made of. Thus, one possible way toincrease ballast volume is to have multiple discrete SPBs in the system.In another embodiment, instead of each SPB being discrete (e.g., formedas separate units that are coupled (mechanically and/or fluidly)together), chambers of the SPB are interconnected through a constrainedchamber and form a configuration having the visual appearance of a“sausage.” Each sausage section then can attain maximum radius for hoopstress, with all chambers connected via the constriction between links.Such an LTA system may comprise a ZPB 200 plus one or more suchsausage-configured SPBs 300.

The LTA systems with multiple SPB's 300, such as the LTA systems 102,103, 104, may have any or all of the same or similar features and/orfunctionalities as the other LTA systems described herein, such as theLTA systems 100 or 101, and vice versa. The SPB's 300 may include one ormore SPB's that form one large, fluidly connected volume that has thevisual appearance of multiple SPB's (e.g., a “sausage” configuration).Thus, some or all of the SPB's 300 may be in fluid communication witheach other. In some embodiments, the multiple SPB's 300 may not be influid communication with each other. For example, fittings 305A may beused. The fitting 305A may be one or more of rope rings, metal fittings,etc. that may separate the internal air compartments of each SPB 300. Insome embodiments, such fittings 305A may allow for air to travel betweenthe various compartments or chambers of the SPB 300, as furtherdescribed herein, for example in the section titled “BALLOON FITTINGS.”Each of the multiple SPB's 300 may be referred to as “SPB compartments”that make up the SPB 300. The SPB 300 may comprise two or more of theSPB compartments. The “compartments” refer to the enlarged portions ofthe SPB 300 having the general shape of the single SPB 300, for exampleas shown in FIG. 1. Thus, FIG. 9C shows two SPB compartments, FIG. 9Dshows three SPB compartments, and FIG. 9E shows four SPB compartments.The SPB 300 may include the SPB compartments connected in series asshown in FIGS. 9C-9E. In some embodiments, the SPB compartments may beconnected in series, in parallel, in other configurations, orcombinations thereof. The two or more SPB compartments of the SPB 300may or may not be in fluid communication with each other. In someembodiments, some of the SPB compartments of the SPB 300 may be in fluidcommunication with some of the other SPB compartments but not in fluidcommunication with other of the SPB compartments. The multiple SPB's 300may be formed separately and then connected together. In someembodiments, the multiple SPB's 300 are formed from the same continuousskin and are either fluidly connected or are “tied off” from each other,either of which configuration may use the fitting 305A, which may be therope rings, metal fittings, etc. There may be a single compressorassembly 800 that provides ambient air to all of the SPB's 300, forexample with multiple air hoses 690 or with a single air hose 690 wherethe multiple SPB's 300 are fluidly connected. In some embodiments, eachSPB 300 may have its own compressor assembly 800 or compressor 810,and/or its own valves 870 and/or 871. Thus, each SPB 300 may have itsown discrete air intake and release assembly. These are merely someexamples of the multiple SPB 300 embodiments of the LTA system and howthey may be implemented, and others not explicitly described herein arewithin the scope of the disclosure. For example, five or more SPB's canbe used, the multiple SPB's need not be configured in a single line(e.g., the system can include hardware from which at least some of theSPB's are coupled laterally relative to each other), etc. Furtherdetails of other embodiments and features for multi-chamber superpressure balloon configurations are provided herein, for example insection “N. CONTINUOUS MULTI-CHAMBER SUPER PRESSURE BALLOON.”

J. Mission-Specific Platforms

The particular configuration of the LTA system 100 and the method of usecan be based on the mission. The various missions may include, forexample, lower altitude missions, higher altitude missions,station-keeping, meteorological purposes, heavy payload lifting, shortduration missions, long duration missions, constellations, handoffs,racetrack, and others. For these and other missions, the LTA system 100and/or the method of use of the LTA system 100 can be accordinglyconfigured.

For example, the LTA system 100 can be configured for higher altitudeand/or heavy payload lifting by including larger volume ZPB 200 and SPB300 and/or the compressor 810 having a larger mass flow rate at lessdense and lower pressure atmospheres. Thus, for higher altitude and/orheavy payload lifting, the LTA system 100 may have a multi-stagecompressor 810, such as a two-stage compressor 810, a ZPB 200 having aninternal volume of about 30,000 cubic meters, and a SPB 300 having aballast capability of +/−100 kilograms. Further, the release valves 870and/or 871 can be configured to allow for a faster mass flow rate, suchas with a larger opening 877 and/or 878 and/or with multiples valves 870and/or 871. Such a system may allow for reaching higher altitudes,larger altitudinal ranges, and doing so at faster speeds.

As another example, the LTA system 100 can be configured for loweraltitude and/or lighter payload lifting by including smaller volume ZPB200 and SPB 300 and/or the compressor 810 having a smaller mass flowrate. This may provide for a lower mass and less complex system. Thus,for lower altitude and/or lighter payload lifting, the LTA system 100may have a single-stage compressor 801, a ZPB 200 having an internalvolume of about 700 cubic meters, and a SPB 300 having a ballastcapability of about +/−50 kilograms. Further, fewer and/or smallerrelease valves 870 can be used, also saving on mass and complexity. Sucha system may allow for reaching lower altitudes and at less cost due tomass savings and less complexity with design of the LTA system 100.

K. Control System

FIG. 10 is a schematic an embodiment of a control system 1000 that maybe used with the various LTA systems described herein, for example theLTA system 100 and 101. In some embodiments, the control system 1000 isin communicating connection with the sensor 740, with the centrifugalcompressor 810, and with the adjustable valve 740, and is configured tocontrol the centrifugal compressor 810 and the adjustable valve 740based at least on one or more detected environmental attributes tocontrol the amount of ambient air inside the SPB 300 to control analtitude of the LTA system 100.

The control system 1000 includes a controller 1010 in communicatingconnection with various components. The communicating connections may bewired or wireless. The controller 1010 is an electronic controller. Thecontroller 1010 is in communicating connection with one or more sensors1020. The sensor 1020 may be the sensor 740 described herein. The sensor1020 detects various parameters and provides corresponding output, forexample data or information, that is communicated to the controller1010. The controller 1010 receives the output from the sensor 1020 todetermine various control operations.

The controller 1010 is in communicating connection with a valve 1030 anda compressor 1040. The valve 1030 and the compressor 1040 may be,respectively, the valve 870 and the compressor 810 described herein. Thevalve 1030 and compressor 1040 are shown as separate components. In someembodiments, the valve 1030 and compressor 1040 may be part of the samesystem, such as the compressor assembly 800 or part of a reversiblecompressor, as described herein. The controller 1010 controls theopening and closing of the valve 870 to cause more or less air to bereleased from the SPB 300. The controller 1010 controls the operation ofthe compressor 810 to cause more or less air to be provided to the SPB300, for example by running the compressor at higher or lower speeds.

The controller 1010 may control the operation of the valve 1030 and/orcompressor 1040 based on output of the one or more sensors 1020, and/orbased on commands sent to the controller 1010 via a communicationssubsystem. For example, light sensors, pressure sensors, thermalsensors, and/or other sensors may detect daylight, ambient pressure,ambient temperature, and/or other parameters, that are analyzed by thecontroller 1010 to control the valve 1030 and/or compressor 1040. Thecontroller 1010 may determine, based on data detected with the sensors1020 and/or received communication signals, that a lower altitude isrequired. Thus, the controller 1010 may send a control signal to thecompressor 1040 to cause the compressor 1040 to provide more air to theSPB 300 to cause the LTA system 100 to descend. Alternatively, thecontroller 1010 may determine, based on data detected with the sensors1020 and/or received communication signals, that a higher altitude isrequired. Thus, the controller 1010 may send a control signal to thevalve 1030 to cause the valve 1030 to release air from the SPB 300 tocause the LTA system 100 to ascend. Further, the controller 1010 maycontrol, in the manner discussed, the rate of air intake or air releasein order to control, respectively, the rate of descent or ascent of theLTA system 100.

The controller 1010 is in communicating connection with a gimbal 1050.The gimbal 1050 may be the gimbal 500 described herein. The controller1010 controls actuation of the gimbal 1050, for example actuation of themotor 510 of the gimbal 500. The controller 1010 controls actuation ofthe gimbal 1050 to control relative rotation of the ZPB 200 and SPB 300,for example to point the solar array 630 is a particular direction. Thecontroller 1010 may control actuation of the gimbal 1050 based on outputof the sensor 1020, and/or based on commands sent to the controller 1010via a communications subsystem. For instance, light detectors, timers,global positioning systems (GPS), LTA system locators that are separatefrom but which communicate with the LTA system 100, and/or other sensors1020, may provide data output or communications to the controller 1010.The controller 1010 may determine, based on data detected with thesensors 1020 and/or received communication signals, that rotation of thesolar array 630 is required. The controller 1010 may then send a signalto the gimbal 1050 to actuate a particular amount. For instance, thecontroller 1010 may send a control signal to the gimbal 500 to cause themotor 510 to operate at a particular speed and/or for a particularamount of time. In some embodiments, the data is detected with thesensors 1020, and/or the communication signals are received,continuously or at regular intervals, such as during daylight, andprovided to the controller 1010 for continuous or interval control ofthe solar array 630. Such operations may allow, for example, fortracking of the sun with the solar array 630 for optimal energyconversion.

The controller 1010 is in communicating connection with a payload 1060and supporting subsystems 1070. The payload 1060 may be the payload 730described herein. The supporting subsystems 1070 may be the varioussubsystem described herein, for example communications subsystem,release mechanisms, etc. The controller 1010 controls various operationsof the payload 1060 and supporting subsystems 1070, for examplegathering data with an optical instrument, taking readings with varioussensors of the subsystems, transmitting and receiving information to andfrom ground stations, satellites, other balloon systems, etc. Thecontroller 1010 may control the payload 1060 and supporting subsystems1070 based on output of the sensor 1020, and/or based on commands sentto the controller 1010 via a communications subsystem. For instance, thecontroller 1010 may send a control signal to the payload 730 to take asample or reading with an optical instrument. As further example, thecontroller 1010 may receive a communication signal to release thepayload support 700, and the controller 1010 may then send a controlsignal to one or more release mechanisms to cause the payload support700 and parafoil 680 to separate from the upper craft 600.

L. Navigation and Control Methods

FIGS. 11-12 depict embodiments of various flight aspects, for examplemaneuvers, trajectories, speeds, etc., that may be performed with thevarious LTA systems described herein, for example with the LTA system100 and 101. Only some example flight aspects of the LTA system 100 aredescribed, and the LTA system 100 has other flight aspects even thoughnot explicitly described. Although the flight aspects are described inthe context of the LTA system 100, it is understood that these aspectsapply equally to other LTA systems described herein, including the LTAsystem 101.

1. Ascent and Descent

FIG. 11A is a schematic depicting embodiments of ascent rates, descentrates and flight ranges that the LTA system 100 is capable of achieving.These aspects are described with reference to various variables for thesake of description only. The aspects shown are approximations togenerally show capability. The LTA system 100 is not limited by thisexample schematic. For instance, the LTA system 100 may ascend higherthan 120,000 feet. As shown, the LTA system 100 begins at point A on theground and ascends to point B at 50,000 feet (“50 k” feet), then ascendsto point C at 100 k feet, and then ascends to point D at 120 k feet. TheLTA system 100 then descends from point D at 120 k feet to point E at100 k feet, then descends to point F at 50 k feet, and then descendsback to ground at point G. The flight path shown from point A to point Gand described herein is for illustrative purposes to show the variouscapabilities of the LTA system 100. The LTA system 100 may follow theflight path shown or other flight paths. In some embodiments, the LTAsystem begins at point A and ascends to point D, then cyclicallydescends and ascends to and from points D and E. In some embodiments,the LTA system begins at point A and ascends to point D, then cyclicallydescends and ascends to and from points D and F. In some embodiments,the LTA system begins at point A and ascends to point C, then cyclicallydescends and ascends to and from points C (or E) and B (or F). After anumber of these or other cycles at high altitude, the LTA system 100 mayrelease the payload support 700 with the parafoil 680 for controlledflight to ground, and the ZPB 200 and SPB 300 may terminate theirflights and fall back to ground, either together or separately.Alternatively, after a number of these or other cycles at high altitude,the entire LTA system 100 may descend back to ground together, throughpoint F to point G. Various sample capabilities of time of flight andspeed of the LTA system 100 for the various ranges and altitudes shownin FIG. 11A are provided in Table 1.

TABLE 1 Sample capabilities of the LTA system for the various ranges andaltitudes shown in FIG. 11A. Altitude Range Time Max Speed Location(feet) (feet) (hours) (feet/hour) A→B   0 → 50k +50k T_(A) → T_(B) = 7.8V_(AB) = 19,200 B→C  50k → 100k +50k T_(B) → T_(C) = 4.3 V_(BC) = 21,600C→D 100k → 120k +30k T_(C) → T_(D) = 4 V_(CD) = 5,000 D→E 120k → 100k−30k T_(D) → T_(E) = 4 V_(DE) = −5,000 E→F 100k → 50k −50k T_(E) → T_(F)= 4.6 V_(EF) = −13,200 F→G  50k → 0 −50k T_(F) → T_(G) = 5.0 V_(FG) =−30,000

FIG. 11B is a flow chart showing an embodiment of a method 1100 forascending and descending with the LTA system 100. The method 1100 may beperformed for example to achieve the ascent and descent rates and rangedescribed with respect to FIG. 11A. The method 1100 may be performedwith the various LTA systems described herein, including the LTA systems100 and 101, and other variations of those LTA systems.

As shown in FIG. 11B, the method 1100 begins with step 1110 wherein aZPB is connected with a pumpkin-shaped SPB. Step 1110 may include theZPB 200 being connected with the SPB 300 in its pumpkin shape orconfigured to be in its pumpkin shape. In step 1110 the ZPB 200 may beconnected directly to the SPB 300, or they may be indirectly connectedfor example via the gimbal 500 or 501. In step 1110 the ZPB and SPB maybe connected in an assembly facility, at the launch pad, or in othersuitable locations.

The method 1100 then moves to step 1120 wherein a centrifugal compressorand valve are fluidly connected with the SPB and with the ambient air.Step 1120 may include the compressor assembly 800 and the valve 870being connected with the SPB 300 via the air hose 690. Step 1120 mayinclude the compressor assembly 800 and the valve 870 being connectedwith the SPB 300 via the air hose 690. The connections may be open suchthat air may flow freely or closed, for example where the valves 870 or871 are closed when connected. Thus, “fluid” connection in step 1120means capable of being in fluid connection. In step 1120 the centrifugalcompressor and valve may be fluidly connected with the SPB and with theambient air in an assembly facility, at the launch pad, or in othersuitable locations.

The method 1100 then moves to step 1130 wherein lift gas is provided tothe ZPB. Step 1130 may include LTA lift gas, such as helium or hydrogen,being provided to the ZPB 200. The LTA gas may be provided to the ZPBvia hose or other suitable means. The various volumes and amounts of LTAgas described herein may be provided in step 1130.

The method 1100 then moves to step 1140 wherein the ZPB 200, SPB 300,compressor 810 and valve 870 are launched to high altitude. Step 1140may include launching to high altitude the LTA system 100 including theZPB 200, the SPB 300, the compressor 810 and the valve 870. Step 1140includes the ZPB 200 with lift gas therein providing the lift to thevarious components. Step 1140 may include the ZPB 200 lifting thevarious components to the upper troposphere, the tropopause and/or thestratosphere.

The method 1100 then moves to step 1150 wherein air is pumped into theSPB 300 with the compressor 810 to descend the ZPB 200, SPB 300,compressor 810 and valve 870. Step 1150 may include the compressor 810pumping air from the surrounding atmosphere at high altitude into theSPB 300 via the air hose 690. Step 1150 may include the LTA system 100descending due to the increased mass of air in the SPB 300, as describedherein. The LTA system 100 may descend in step 1150 as described forexample with respect to FIG. 11A.

The method 1100 then moves to step 1160 wherein air is released from theSPB 300 with the valve 870 to ascend the ZPB 200, SPB 300, compressor810 and valve 870. Step 1160 may include the valve 870 releasing airfrom the SPB 300 via the air hose 690 into the surrounding atmosphere athigh altitude. Step 1160 may include the LTA system 100 ascending due tothe decreased mass of air in the SPB 300, as described herein. The LTAsystem 100 may ascend in step 1150 as described for example with respectto FIG. 11A.

The method 1100 may be repeated in various manners. For example,multiple LTA systems 100 may be launched and flown as described in themethod 1100. As further example, steps 1150 and 1160 may be repeatedafter performing steps 1110 to 1140. In some embodiments, some or all ofthe steps of the method 1100 may be performed, and the flight may beterminated, for example in the various manners described herein. Forexample, steps 1110 to 1140 may be performed and then steps 1150 and1160 may be cyclically repeated multiple times, after which the LTAsystem 100 flight may be terminated as described.

The LTA system 100 can be used for a variety of different missions. TheLTA system 100 can be used to remain airborne for longer durations, forexample during stratospheric flights with sustained communications. TheLTA system 100 can be used to maintain a fairly constant footprint onthe ground, particularly in the case of observation and communications.The LTA system 100 thus enables altitude maintenance during diurnalvariations in solar elevation as well as station-keeping for largeportions of the year worldwide. Some embodiments of a station-keepingpersistence envelope with active altitude control that may be performedwith the LTA system 100 are described herein.

2. “Barber Pole” Station-Keeping

FIG. 12A is a schematic depicting an embodiment of a persistenceenvelope for high altitude station-keeping with the LTA system 100. Theenvelope includes an upper portion of the troposphere, the tropopause,and the stratosphere. Boundaries between these layers of the upperatmosphere are indicated by the two dashed lines.

As shown in FIG. 12A, the LTA system 100 begins at point J in the uppertroposphere. The LTA system 100 then travels from point J to point Kalong the path X₁. The LTA system 100 travels along the path X₁ due tothe prevailing winds. Point K is approximately at the same altitude aspoint J. In some embodiments, point K may be at a different altitudethan point J. The point K corresponds to latitude and longitudecoordinates within a first range of latitude and longitude coordinates.The first range of latitude and longitude coordinates may correspond tofavorable locations of the tropopause through which it is desirable forthe LTA system 100 to ascend. At point K, the LTA system 100 ascends.The LTA system 100 ascends by releasing air, for example by controllingthe valve 870 to release air from the SPB 300. The LTA system 100 maythen ascend from the upper troposphere and into the tropopause.

The LTA system 100 ascends through the troposphere along the path Y₁.The path Y₁ is a helix or an approximate helix through the tropopause.Thus, the LTA system 100 ascends along a helical path, or “barber pole.”The trajectory that the LTA system 100 travels is helical through thetropopause because of the first range of latitude and longitudecoordinates correspond to a portion of the tropopause having varyingwind directions at different altitudes. It should be noted that varyingwind directions may be found in all parts of the atmosphere, and “ridingon the barber pole” is not limited to operations only in the tropopause.The LTA system 100 can thus take advantage of varying wind directionsanywhere within its altitude changing range. Thus, the descriptionherein of the helical path with respect to particular portions of theatmosphere, such as the tropopause, is not meant to limit the use of theLTA system 100 in that manner to only those areas.

The wind directions in the tropopause, and/or in other portions of theatmosphere, angularly vary at varying altitude such that the LTA system100 travels along the helical path. The path Y₁ has an approximatediameter D₁ as indicated. The diameter D₁ varies depending on the speedof the winds and the rate of ascent of the LTA system 100. The rate ofascent can be controlled based on the rate of release of air from theSPB 300. Thus, the diameter D₁ of the helical path Y₁ can be affected bycontrolling the rate of release of air from the SPB 300. For example,air may be released at a relatively slower rate such that the LTA system100 ascends at a relatively slower rate. Thus, the LTA system 100 willspend more time in any one of the various layers of the tropopausehaving varying wind directions, and so the helical path Y₁ will have alarger diameter D₁. Conversely, for example, air may be released at arelatively faster rate such that the LTA system 100 ascends at arelatively faster rate. Thus, the LTA system 100 will spend less time inany one of the various layers of the tropopause (or any part of theatmosphere the LTA 100 system is operating) having varying winddirections, and so the ideally helical path Y₁ will have a smallerdiameter D₁. By varying the speed of ascent or descent of the LTA system100, these helical trajectories can be modified so that the flight stayswithin a desired range of latitude and longitude coordinates.

At point L, the LTA system 100 stops ascending. For example, the LTAsystem 100 may stop releasing air from the SPB 300. As further example,the LTA system 100 may have already stopped releasing air and the LTAsystem has now reached its maximum or equilibrium altitude. From pointL, the LTA system travels along the path X₂ to point M. The path X₂ isin a different direction than that of the path X₁. In some embodiments,the path X₂ is in the opposite direction than that of the path X₁. Thepoint M is at the same or similar altitude as the point L. In someembodiments, the point M may be at a different altitude than the pointL.

The point M corresponds to latitude and longitude coordinates within asecond range of latitude and longitude coordinates. The second range oflatitude and longitude coordinates may correspond to favorable locationsof the tropopause through which it is desirable for the LTA system 100to descend. The second range of latitude and longitude coordinates mayinclude all, some or none of the coordinates within the first range oflatitude and longitude coordinates. For example, the first and secondrange of latitude and longitude coordinates may be identical. As furtherexample, the first and second range of latitude and longitudecoordinates may share some of the same coordinates, i.e. may beoverlapping. As further example, the first and second range of latitudeand longitude coordinates may not share any of the same coordinates,i.e. may be entirely separate and not overlap at all. At point L, theLTA system 100 descends. The LTA system 100 descends by moving air intothe SPB 300, for example by controlling the compressor 810 to causeambient air from the surrounding atmosphere to flow into the SPB 300.The LTA system 100 may then descend from the upper troposphere and intothe tropopause.

The LTA system 100 descends through the troposphere along the path Y₂.The path Y₂ is a helix or an approximate helix through the tropopause.The path Y₂ traveled by the LTA system 100 is similar to the path Y₁ butin the opposite direction, and possibly at different latitudes andlongitudes than the path Y₁. Thus, the LTA system 100 descends along ahelical path Y₂, or “barber pole.” The trajectory that the LTA system100 travels is helical through the tropopause because the second rangeof latitude and longitude coordinates corresponds to a portion of thetropopause having varying wind directions at different altitudes. Thewind directions angularly vary at varying altitude such that the LTAsystem 100 travels downward along the helical path Y₂. The path Y₂ has adiameter D₂ as indicated. The diameter D₂ varies depending on the speedof the winds and the rate of descent of the LTA system 100. The rate ofdescent can be controlled based on the rate air intake into the SPB 300.Thus, the diameter D₂ of the helical path Y₂ can be affected bycontrolling the rate of air intake into the SPB 300. For example, thecompressor 810 may be operated at a relatively slower speed such thatair is taken in at a relatively slower rate, so that the LTA system 100descends at a relatively slower rate. Thus, the LTA system 100 willspend more time in any one of the various layers of the tropopausehaving varying wind directions, and so the helical path Y₁ will have alarger diameter D₂. Conversely, for example, air may be taken into theSPB 300 at a relatively faster rate such that the LTA system 100descends at a relatively faster rate. Thus, the LTA system 100 willspend less time in any one of the various layers of the tropopausehaving varying wind directions, and so the helical path Y₁ will have asmaller diameter D₂.

After descending through the tropopause along the path Y₂ and into theupper troposphere, the LTA system 100 stops descending. For example, theLTA system 100 may stop descending by ceasing to take in more air intothe SPB 300. As further example, the LTA system 100 may have alreadystopped taking in air into the SPB 300 and the LTA system 100 has nowreached a minimum or equilibrium altitude. The LTA system may exit thetropopause and stop ascending in the upper troposphere after returningto point J, as shown. In some embodiments, the LTA system may exit thetropopause and stop ascending in the upper troposphere at a point otherthan at point J. For example, the LTA system 100 may stop ascending at adifferent altitude than point J. As further example, the LTA system 100may stop ascending at a same altitude as point J but laterally at adifferent location, i.e. at different latitude and/or longitudinalcoordinates. As another example, the LTA system may stop ascending at adifferent altitude and at a different lateral position than point J.

From point J, or from another point where the LTA system stopsdescending, the LTA system may travel laterally within the uppertroposphere. As shown, the LTA system 100 may travel from point J alongthe path X₁ to point K. In some embodiments, the LTA system 100 maytravel along a path different from the path X₁. In some embodiments, theLTA system 100 may travel from point J along a path to latitude andlongitude coordinates that are different from point K but which arewithin the first range of latitude and longitude coordinates. In someembodiments, the LTA system 100 may travel from point J to a locationthat is not within the first range of latitude and longitudecoordinates.

3. Altitude Control Coverage Patterns

A variety of different trajectories may be flown with the LTA system 100to establish persistent coverage. This section presents three altitudecontrol coverage patterns that can be used with the LTA system 100 toprovide persistent coverage over an area of interest (AOI). Thesepatterns are the Single Pass Coverage (SPC), Multiple Pass OrbitalCoverage (MPOC), and the Station-Keep Coverage (SKC) flight patterns. Toprovide persistent coverage, these patterns may be used in combination.Prior to a mission, forecasting tools, wind scoring (see below), etc.may be used to establish the coverage patterns needed to meetpersistence requirements and hence identify the launch locations andlaunch frequencies (i.e., constellation requirements). The trajectorysimulations presented show four scenarios where SKC and MPOC coveragepatterns are applicable. In all cases, the SPC flight pattern may beused, but may not be the most cost effective option.

The LTA system 100 offers a platform with direct line of sight (LOS)coverage of an area of interest (AOI) for extended durations. The LTAsystem 100 may have its trajectory altered so as to remain within directLOS of the AOI. The LTA system 100 can accomplish this by ascending ordescending to different altitudes that hold wind speeds and directionsfavorable to a return trajectory. A given mission will require directLOS coverage for distinct periods of time separated by intervals with nocoverage. Meeting this schedule of direct LOS coverage is defined aspersistent coverage.

To establish persistent coverage over an AOI, the LTA system 100provides ascent and descent rate capabilities over an altitude rangethat encompasses a variety of wind directions. Many factors go intodetermining the degree to which persistent coverage over a region ispossible, as well as the methods and costs involved in doing so. Theprimary factors include the AOI ‘regional’ winds and the time of year ofthe operation. The proposed operating regime here is within the uppertroposphere, the tropopause and the stratosphere. In the stratosphere,average wind patterns vary from month to month and from location tolocation. These and other features of the upper atmosphere areadvantageously used by the LTA system 100.

Of particular significance to flight of the LTA system 100 at highaltitudes is the characterization of wind speed and direction withlocation, altitude, and time of year. The general wind patterns based onaltitude and time of year present an organizational structure. Thisorganizational structure allows one to roughly establish the altitudechange required to “station-keep” over any given place for any givenmonth.

Our typical experience with winds is naturally tied to the troposphere,where regional conditions, and localized convection made possible by thetropospheric temperature gradient, create a chaotic wind environment.The altitude of the tropopause varies. It is approximately 15 km (˜120mb) in the equatorial region and 9 km (˜300 mb) in the polar region. Aswe go higher into the atmosphere, the regional differences have lesseffect, and broader patterns emerge. Within the stratosphere, winds aregenerally driven by the global distribution of absorbed solar heat, andthe Coriolis effect. Near the equator, upper winds almost always blowprimarily out of the east, with increasing variability pole-wards.Winter at the given pole tends to result in very strong winds blowingout of the west (westerly), while a polar summer tends to result inslower, more varied, easterly winds. The change in direction, referredto as the ‘turnaround’, occurs twice a year, typically May and October.

The Single Pass Coverage (SPC) pattern is used with the LTA system 100if no circulatory pattern exists in the region about the AOI. In thisscenario, the LTA system 100 would be launched at a point upwind,allowed to float over the AOI, and then returned to the ground at apoint downwind of the AOI. Multiple launch and recovery options areafforded by the use of the altitude control capabilities of the LTAsystem 100. Although this tactic can always be used, it is the mostexpensive option as multiple LTA systems 100 will need to be deployed tomeet the mission persistence requirement.

The Multiple Pass Orbital Coverage (MPOC) pattern can be used with theLTA system 100 if a circulatory pattern exists in the region about theAOI that allows the LTA system 100 to return back over the AOI multipletimes. The circulation does not need to be continuous in a singlestratum, as the return trajectory can take place over multiple strata.The size of the loop and the persistence requirement will dictate thenumber of LTA systems 100 that must be flown. This option can greatlyreduce hardware and operations cost for long duration missions.

The Station-keep Coverage (SKC) pattern can be used with the LTA system100 when wind speeds over the AOI are low and the direction is variable.Under these favorable conditions, a balloon can loiter over an AOI foras long as the weather pattern supports it.

These different coverage patterns are necessary to accommodate thevariability in local wind pattern from location to location and the timeof year. In addition, long duration missions may occur across severalweather patterns and thus require a combination of deployment tactics tomeet persistence objectives. Opportunities to fly the MPOC and SKCcoverage patterns improve when the winds are slow and varied. SPC may bepreferably used when the winds are uniformly directional at alloperational altitudes. The ability to change altitude can improve thechance for cost-efficient persistence coverage maneuvers if the windvectors are favorable at the other altitudes. For instance, the windpattern at the higher altitudes, e.g., 10 mb and 20 mb, do not differmuch. The main difference between these two altitudes is in velocitymagnitude. The probability of finding different wind directions improveswhen the operating range is extended down to 100 mb. These observationsare based on averaged velocities and actual winds may offer greateropportunities.

A mission plan for the LTA system 100 would begin with a review ofhistoric wind data to determine if altitude control balloon technologyis applicable. The probability for having light and variablestratospheric winds varies by location and time of year but in generalthere exists a fairly high probability of station keeping windsworld-wide throughout a large portion of the year. If the LTA system 100is appropriate, the mission plan would then focus on the coveragepatterns available to establish persistent coverage. The mission planwould be based on wind analyses of actual forecasted data and trajectorysimulations performed in the weeks leading up to the mission, for theAOI and time of interest. The plan would be periodically revised withupdated forecast data. It would be necessary to continue these revisionsinto the mission itself for long duration missions. LTA system 100trajectory calculations would be based on actual forecasted wind datathat resolve both spatial and temporal differences around the AOI.

Prior to doing trajectory simulations for the LTA system 100, theforecasted winds would be processed to determine if MPOC and SKCcoverage patterns are feasible and if so to what extent. Computeranalysis tools may be used to process historic data and forecast data tohelp identify and/or visualize the likely locations, times, and moreimportantly the altitudes by which MPOC and SKC patterns are possible,or if the mission must be accomplished with the SPC pattern. Thesoftware may analyze the raw radiosonde data using data analysis modulesto determine the types of wind. The winds are characterized in 3 types:Type 0a, Type 1 and Type 2. Type 0a refers to light and highly variablewinds spanning the compass within a defined region. Type 1 refers tobalanced winds in both directions of zonal and meridional flow. Type 2refers to stable, optimal zonal shear pattern winds.

The mission plan for the LTA system 100 would be finalized by performingtrajectory simulations using actual forecasted wind data. Thesesimulations would identify the coverage patterns (SPC, MPOC, and/orSKC), launch locations and timing, and approximate recovery locationsand timing. The trajectory simulations employ a fourth-order Runge-Kuttaintegration scheme to calculate trajectory from acceleration andvelocity. Wind speed and direction are linearly interpolated in timefrom one-time period to the next (6 hours apart), linearly in latitudeand longitude, and using a continuously differentiable Akima spline inaltitude. Balloon ascent and descent rates can either be assumedconstant or determined through the solution of the complete set of LTAsystem 100 performance governing equations (force and heat balanceequations). Ascent and descent commands can either be input manually(flight simulator mode) or using an auto-pilot control algorithm.

In cases where the operating altitude for the LTA system 100 over theAOI is prescribed due, for example, to specific sensor requirements, itmay not be possible to use SKC even if wind conditions accommodated suchan operation over the AOI. In these cases, SPC or MPOC will be used,however the principals of SKC become highly advantageous to the overalloperation when the vehicle is not in the AOI. For example, the SKC windpatterns could greatly simplify SPC operations by allowing the LTAsystem 100 to be launched from a base or ship, navigate to the up-windlocation for entering the AOI, and then ascend or descend to theoverflight operating altitude for the fly-over. Clearing the AOI, theLTA system 100 can then use the winds to maneuver within range of thelanding site to potentially navigate around the AOI in an MPOCoperation.

4. Wind Data Analyses

Identification of the various regions of the upper atmosphere havingfavorable wind conditions may be based on a variety of approaches. Insome embodiments, the sensors 740 may provide data related to winddirection, temperatures, pressures, etc. that assist with determiningthe ideal wind conditions. In some embodiments, data from other LTAsystems 100 already in flight may provide information regions with idealwind conditions. For instance, multiple LTA systems 100 may be used in aconstellation, and data gathered from each LTA system 100 may beanalyzed to inform the other LTA systems 100 in the constellation ofideal wind condition locations. In some embodiments, data may bereceived from non-LTA system balloons that are in flight. In someembodiments, data may be received from meteorological instruments, suchas from satellites or ground systems.

In some embodiments, these and/or other sources of data, in conjunctionwith the basic system design of the LTA system 100, may be used forachieving enhanced guidance, navigation and control (GNC) as compared totypical LTA systems. In some embodiments, such enhanced GNC is achievedby the combination of the advanced features of the LTA system 100 forrapid descent/ascent, along with analysis of a mission planning based oncertain wind data. Such wind data may include data on the varying windspeeds and directions stratified within the troposphere, tropopause,and/or stratosphere. For example, at certain times of the year, and incertain locations that are less conducive to station-keeping operations,the LTA system 100 allows for constellation flight operations tomaintain constant line of site with multiple tandem balloon systemfly-overs. In some embodiments, this and/or other data is used toproduce “wind scores” for GNC purposes.

The LTA system 100, for example the control system 1000, can analyzeglobal winds at high altitudes, for example in the stratosphere, todetermine optimal station-keeping navigation around the world and yearround. The LTA system identifies long-term patterns from winds that arevariable, shifting and unpredictable over the short term. In someembodiments, the LTA system 100 analyzes such data and determines overlong periods that radiosonde data of winds may vary greatly only 12hours apart in the same location, but that there are exploitablelonger-term patterns that persist for days or weeks and are consistentfrom year to year.

The LTA system 100 and/or supporting systems such as ground stationsanalyzes the various data about winds and identifies corresponding GNCcontrol algorithms and techniques for optimal flight. For instance,zonal winds (east/west) typically have a very consistent pattern overthe course of a year. In many places, particularly latitudes between 20and 60 degrees north and south, zonal winds blow predominantly in onedirection at low altitudes, then cross over to the opposite direction inthe lower stratosphere, then generally switch back to the originaldirection higher in the stratosphere. Equatorial and polar conditionscan be less predictable.

Meridional winds are far more chaotic. However, some patterns arepresent, in two ranges. The upper range is characterized bypredominantly north or south winds, with small pockets of the oppositedirection interspersed unpredictably (in time and space) throughout.Within the lower range (from roughly 20 km down to the aviationrestriction boundary) a condition of strong meridional wind, in onedirection or another, is frequently present. Such winds may beidentified that exist strongly within a particular altitude and do notchange any further in the wind column downwards. The pattern may be thatthe winds blow north for a week, are neutral for a week, blow south fora week, and so forth. The LTA system 100 or related systems may identifyor determine a signature, or fingerprint, that is fairly unique to eachregion based on analysis of the winds over longer periods, for instanceover the course of a year. The LTA system 100 may determine that thezonal winds are fairly consistent and predictable, and the meridionalwinds are mostly chaotic in the upper range, with odd bands of periodicresonances (on the order of a week or so) present in the lower range.The LTA system 100, for example the control system 1000, may determine anavigational trajectory accordingly.

Trajectories for the LTA system 100 may be determined based on variouswind scoring or rating approaches. One such approach is described here.Medium period wind patterns, currently defined as being significant for12-60 hours, are particularly important when it comes to meridionalnavigation, since those winds shift so quickly and randomly. In thisperiod, the GNC and related control algorithms of the LTA system 100 mayanalyze regions of air, not particular heights. In order to define thesewind regions, the wind scoring algorithm starts with a simple weightedmoving average over a set of vertical samples, which may be for examplefrom nearby radiosonde flights, or from the LTA system 100 flightitself, such as sensors 740. The weighting may be a simple linear weightbased on the distance from the center sample. Distances further than 500meters may be ignored. A fixed window of nine samples may be used. Greenregions (light and variable) are identified by having a weightedstandard deviation greater than the magnitude of their mean, on bothhorizontal axes, across a span of altitudes. They are presently scoredfor their “quality” by scaling their mean winds by the ratio of theirstandard deviation to their mean, on each axis, and summing the tworesults. This emphasizes the primary importance of low mean windmagnitude, while secondarily taking into account wind turbulence, lowerscores obviously making them better green regions. It is the absolutevalue of the mean that the algorithm is looking for, in this case. Thealgorithm rates these winds using a “green score,” which may bedetermined as shown here:

${{green}\mspace{14mu} {score}{= {{Z_{mean}\left( \frac{Z_{mean}}{Z_{std}} \right)} + {M_{mean}\left( \frac{M_{mean}}{M_{std}} \right)}}}},{Z_{std} > {Z_{mean}}},\ {M_{std} > {{M_{mean}}.}}$

Green winds may be an optimal area to remain in for station-keeping, asit signifies a likelihood that that many wind directions can be found.Further, in this area the winds are consistently blowing at low speeds,which may be about five meters per second or less.

This is merely an example of how wind data may be analyzed and used bythe LTA system 100. Other approaches may be implemented, including butnot limited to those described, for example, in U.S. provisional patentapplication No. 62/294,204, entitled SEMI-AUTONOMOUS TRAJECTORY CONTROLFOR BALLOON FLIGHT and filed Feb. 11, 2016, the entire disclosure ofwhich is incorporated by reference herein for all purposes. Forinstance, “yellow” and “blue” regions may be identified, as describedtherein, that omit the other horizontal axis in the calculation.

The GNC algorithm may comprise multiple layers. At the highest level, isthe overall mission intent, be it station-keeping, or path control.Below that is the direction layer. The mission layer consists of anobjective, and considers the present location of the balloon. Theobjectives can be to station-keep within a particular range, or totravel to a particular nearby location (within a few hundred kilometers;accuracy best if direction is primarily zonal). One example of aprocedure is described below:

1. The mission for the LTA system 100 is planned, and long-termparameters may be set, based on observation of long-term trends.Tolerances of station keeping are specified by maximum range separatelyin zonal and meridional directions to accommodate the disparity in windavailability (typically much more zonal slack than meridional, as zonalposition is easier to fix, and it's often necessary to drift off-centerzonally in order to correct meridional position).

2. On-board system may maintain a set of wind observations, recordingspeed, direction, and timestamp. Some post-processing may need to beperformed to clean the raw data. The sensors may be mounted to theballoon itself, and not to anything susceptible to oscillations internalto the payload support 700 and related systems. For semi-autonomousnavigation of the LTA system 100 (e.g. not relying on transmitted dataafter launch), data store can be pre-populated with the most recentavailable radiosonde data.

3. Periodically, medium period zones (Green, Yellow, Blue, High, andLow) may be recalculated, based on newly gathered and binned data. Thecalculations are fairly simple, so should not impose too much processingload.

4. Station-keeping mission layer may proceed as follows:

-   -   a. Initial height set to zonal floor, with no directional goal.    -   b. Periodically query data store for wind availability. In North        America, where/when station-keeping is possible, there will        almost always be one rare wind (north or south). This is the        priority wind. It will narrow the bounding box such that the        system attempt to keep asymmetrically further in the direction        in which the rare wind blows out of:    -   c. Once target height is initially reached, if system is within        horizontal bounds, preferentially drift upwards (during solar        heating) or downwards (at night) towards calmest winds.    -   d. If the system encounters a boundary on an axis, set main goal        to the horizontal direction opposite that boundary. Prefer        travel in the same vertical direction as the above case.    -   e. Alter the request to the direction subsystem when direction        goal changes. Direction goal is thus one of the four cardinal        directions.    -   f. Do not alter goal direction, until either reaching the        opposite boundary, or, if out of bounds on both axes, switch        priorities periodically (subject to hysteresis) to the direction        furthest out of bounds.

Below that is the direction layer which has long period parameters. Itmust translate high-level direction goals into desired heights. Itutilizes hard data to the extent it can, and shifts to heuristic data,where the hard data has expired, or where it is not available. A verysimple heuristic is used to guide the balloon to the resulting altitudearea, whereupon fine-tuning can be done by direct measurement. Oneexample of the procedure is as described as follows:

1. Zonal Ceiling: Above this height, the zonal winds cross over a secondtime, and do not seem to change any further up, all the way to ouraltitude ceiling. The exact ceiling (and other floors/ceilings) can beupdated in flight. May be set to 0, if unknown, in which case it is notconsidered.

2. Zonal Floor: Similar to Zonal Ceiling, below the zonal floor, zonalwinds do not change significantly, all the way down to aviationrestriction altitude(currently considered 45 k feet, or 13.7 km)

3. Zonal Wind Directions: specified as a simple set of positive ornegative values indicating sign of zonal wind below the zonal floor,between the zonal floor and ceiling, and above the ceiling.

4. Meridional Floor: This is a “decision” altitude. If, on a downwardexcursion, the balloon has not encountered a strong (e.g., >5 m/s)meridional wind in the desired direction (i.e. not neutral, and not theopposite direction) then there's no point in traveling any further downin the pursuit of better meridional winds. The craft will have to makedo with whatever north/south wind components are available above.

5. Wind Priority (optional): This can be automatically determined inflight, but is something that could be known prior to flight. East/Westcontrol is reliably present, or reliably absent. North or South may beavailable as well, depending on the conditions in the lower range. Thisleaves one direction always out, and often two. If only one winddirection is missing, it is considered the priority wind, and the systemneeds to spend as much time as possible in those winds, when it findsthem, because they may be absent later. See description and figureabove.

An objective of the algorithm may be described as follows:

1. Zonal control is cheap, where and when available. Meridional isgenerally fleeting.

2. Where a zonal crossover is available, green zones(ideally) or yellowzones(see zone section) as close as possible to the crossover, are theideal place to hunt for zonal corrections, particularly if acorresponding green/yellow zone exists on the opposite side of thecrossover, to toggle back and forth(avoiding excessive zonaldeflection). This is because they are known to not have strong diagonalcomponents, preventing deviation on the unintended axis.

3. By the same token, when primarily interested in large meridionalcorrections, blue zones of the appropriate sign are welcome. But bluezones are typically only on one side of the axis, so they are frequentlyof limited station-keeping use.

4. Generally, slower winds are always better for station-keeping, evenif they aren't perfect, as they can be ridden for longer beforerequiring corrections.

The direction system attempts to maintain mission layer's direction, atthe lowest possible speed. One embodiment is described here:

1. East/West goal: proceed to nearest green zone in the currentdirection of vertical travel. Failing that, the yellow zone with zonalwinds of the appropriate direction. Failing that, the zonal boundary,stopping when the desired wind is reached in all cases. If not possiblein the desired direction of travel, search in the opposite direction forall of the above. If for some reason it doesn't succeed, just go to theslowest wind region, wait some period of time, and try again.

2. North/South goal: If a North/South wind has been observed atmeridional floor, and it matches what's needed, proceed directly to it.If it hasn't been observed for 72 hours, also proceed directly to it toobserve it. Otherwise, the algorithm is the same as the East/West goal,except substituting “blue” for “yellow”. Most likely, no good zones willbe available, and the system will have to make do with what it finds, inthe calmest possible regions of the wind column.

The height system translates the height request into an action for theballast system of the compressor assembly 800 and the SPB 300(add/remove/hold). It calculates the amount of air needed in the SPB 300to balance out at the desired geopotential altitude, and runs thecompressor 810 (or vents air ballast) until this is accomplished. Whenthe predicted altitude is reached, additional fine-tuning may beperformed, to fine-tune the direction. Wind navigation may takeprecedence over the mission-specified ideal altitude, in order to makethe problem more tractable.

In some embodiments, various mission objectives require the LTA system100 to maintain a presence within a particular segment or segments ofthe upper atmosphere. For example, the segment may be determined basedon communications, line of sight, reconnaissance, or other requirements.Thus, the LTA system 100 may be required to maintain a presence in agiven segment to achieve these or other objectives. The particularsegment or segments may be bounded by one or more latitude and longitudecoordinates, radii, and/or various altitudes. In some embodiments, theLTA system maintains a presence within such segments by use of the“barber pole” technique described above. The LTA system 100 may thuspersist within the envelope shown in FIG. 12A using the various featuresdescribed herein and traveling along the cyclical path described above.For instance, the valve 870 and compressor 810 may be controlled toachieve descent and ascent of the LTA system 100 at precise locations ofthe upper atmosphere to stay within the envelope of FIG. 12A for aprolonged period of time. In some embodiments, the LTA system 100 maycyclically travel along the same or approximately the same closed pathshown in FIG. 12A. In some embodiments, the LTA system 100 may notcyclically repeat the path shown in FIG. 12A but still maintain asufficient envelope. For example, a range of altitudes and latitude andlongitude coordinates may be determined that will allow the LTA system100 to achieve a mission objective. The LTA system 100 may then travellaterally in the upper troposphere and stratosphere along differentpaths for similar segments (paths X₁ or X₂) of the barber-pole cycle.Similarly, the LTA system 100 may ascend or descend through thetropopause along different paths for similar segments (paths Y₁ or Y₂)of the barber pole cycle.

The barber pole approach may be more efficient than merely ascending anddescending continuously at the same or similar latitude and longitude.For instance, as mentioned, a mission objective may still be achieveddespite a larger envelope in the lateral direction, which may be causedby the lateral travel of the barber pole approach, for example lateraltravel along the paths X₁ and X₂. This in effect allows the ascent anddecent systems to rest and not use power during the lateral segments.Thus, the LTA system 100 may maintain a sufficient envelope but withless expenditure of power for releasing or taking in air compared toother approaches. Further, identification of slow moving layers, forexample by using the wind scoring techniques, may further allow forgreater power savings due to slower movement in the lateral direction.Identification of slower wind layers within the tropopause may also beused for power savings, where ascent and descent rates can be slower,creating larger diameter helical paths but which are still within thedesired envelope.

FIG. 12B is a flow chart showing an embodiment of a method 1200 forstation-keeping with the LTA system 100. The method 1200 may beperformed for example to achieve the persistence envelope described withrespect to FIG. 12A. The method 1200 may be performed with the variousLTA systems described herein, including the LTA systems 100 and 101, andother variations of those LTA systems.

As shown in FIG. 12B, the method 1200 begins with step 1210 wherein afirst range of latitude and longitude coordinates are determined. Step1210 may include determining a first range of latitude and longitudecoordinates corresponding to a first portion of the tropopause having afirst plurality of altitudes corresponding respectively to a firstplurality of wind directions within the tropopause. Step 1210 may beperformed by the control system 1000. In some embodiments, step 1210 isperformed by onboard computers and/or sensors, such as the sensors 1010and/or the supporting subsystems 1070. In some embodiments, step 1210 isperformed by ground stations or other LTA systems and the coordinatesare communicated to the LTA system 100. Step 1210 may involveidentifying a range that includes the point K of FIG. 12A. In someembodiments, step 1210 may include moving the LTA system 100 within thefirst range of latitude and longitude coordinates. In some embodiments,step 1210 includes the LTA system 100 traveling in a generallyhorizontal first direction through the troposphere to one of thecoordinates of the determined first range of latitude and longitudecoordinates.

The method 1200 then moves to step 1220 wherein air is released with avalve from the SPB 300 from within the first range of latitude andlongitude coordinates. Step 1220 may include release air from the SPB300 with the valve 870 while the LTA system 100 is within the firstrange of latitude and longitude coordinates. Step 1220 may be performedin the upper troposphere or in the tropopause. In some embodiments, step1220 includes controllably releasing, with the adjustable valve 870, theambient air from the SPB 300 to ascend the LTA system 100 from thedetermined first range of latitude and longitude coordinates within thetroposphere and through the tropopause to the stratosphere, wherein theLTA system 100 travels along a first helical trajectory through thetropopause due to the first plurality of wind directions at the firstplurality of altitudes within the tropopause, wherein the LTA system 100ascends at a plurality of ascent rates through the tropopause, andwherein at least one of the plurality of ascent rates is at least 10,000feet per hour.

The method 1200 then moves to step 1230 wherein the LTA system ascendsalong an upward helical trajectory. Step 1230 includes the LTA system100 ascending due to the release of air and the resulting lower mass ofair ballast in the SPB 300. Step 1230 may include the LTA system 100ascending along a helical trajectory through the tropopause. Forexample, in step 1230 the LTA system 100 may ascend along the path Y₁and/or to the point L of FIG. 12A. Step 1230 may include the LTA system100 ascending to the stratosphere.

The method 1200 then moves to step 1240 wherein a second range oflatitude and longitude coordinates are determined. Step 1240 may includedetermining a second range of latitude and longitude coordinatescorresponding to a second portion of the tropopause having a secondplurality of altitudes corresponding respectively to a second pluralityof wind directions within the tropopause. In step 1240 at least one ofthe coordinates of the first range of latitude and longitude coordinatesmay not be within the second range of latitude and longitudecoordinates. Step 1240 may be performed by the control system 1000. Insome embodiments, step 1240 is performed by onboard computers and/orsensors, such as the sensors 1010 and/or the supporting subsystems 1070.In some embodiments, step 1240 is performed by ground stations or otherLTA systems and the coordinates are communicated to the LTA system 100.Step 1240 may involve identifying a range that includes the point M ofFIG. 12A. In some embodiments, step 1240 may include moving the LTAsystem 100 within the second range of latitude and longitudecoordinates. In some embodiments, step 1240 includes the LTA system 100traveling in a generally horizontal second direction through thestratosphere to one of the coordinates of the determined second range oflatitude and longitude coordinates. In some embodiments of step 1240,the second direction traveled is different from the first direction thatmay be traveled in step 1210.

The method 1200 then moves to step 1250 wherein air is pumped into theSPB 300 with a compressor 810 from within the second range of latitudeand longitude coordinates. Step 1250 may include pumping air into theSPB 300 with the compressor 810 while the LTA system 100 is within thesecond range of latitude and longitude coordinates. Step 1250 may beperformed in the upper troposphere or in the tropopause. In someembodiments, step 1250 includes controllably pumping, with thecompressor 810, the ambient air into the SPB 300 to descend the LTAsystem 100 from the determined second range of latitude and longitudecoordinates within the stratosphere and through the tropopause to thetroposphere, wherein the LTA system 100 travels along a second helicaltrajectory through the tropopause due to the second plurality of winddirections at the second plurality of altitudes within the tropopause,and wherein the LTA system 100 descends at a plurality of descent ratesthrough the tropopause, and wherein at least one of the plurality ofdescent rates is at least 10,000 feet per hour.

The method 1200 then moves to step 1260 wherein the LTA system descendsalong a downward helical trajectory. Step 1260 includes the LTA system100 descending due to the pumping in of air and the resulting highermass of air ballast in the SPB 300. Step 1260 may include the LTA system100 descending along a helical trajectory through the tropopause. Forexample, in step 1260 the LTA system 100 may descend along the path Y₂and/or to the point J of FIG. 12A. Step 1260 may include the LTA system100 descending to the upper troposphere.

The method 1200 may be cyclically repeated in various manners. Forexample, multiple LTA systems 100 may be launched and flown as describedin the method 1200. As further example, steps 1210 through 1260 may berepeated for maintaining the LTA system 100 within a persistenceenvelope, such as the envelope of FIG. 12A. In some embodiments, themethod 1200 is cyclically repeated for maintaining the LTA system 100within a persistence envelope comprising portions of the troposphere,tropopause and stratosphere, where maintaining the balloon system withinthe persistence envelope comprises cyclically repeating the following:i) the LTA system 100 traveling, from a starting position within thetroposphere corresponding to one of the coordinates of the second rangeof latitude and longitude coordinates, along the generally horizontalfirst direction through the troposphere to a first location of thetroposphere corresponding to one of the coordinates of the first rangeof latitude and longitude coordinates; ii) the LTA system 100 ascendingfrom the first location of the troposphere through the tropopause alongthe first helical trajectory to a second location within thestratosphere; ii) the LTA system 100 traveling along the generallyhorizontal second direction from the second location of the stratosphereto a third location of the stratosphere corresponding to one of thecoordinates of the second range of latitude and longitude coordinates;and iv) the LTA system 100 descending from the third location of thestratosphere through the tropopause along the second helical trajectoryto an ending position within the troposphere corresponding to one of thecoordinates of the second range of latitude and longitude coordinates.

M. Performance Simulations

The simulated performances of various embodiments of the LTA system 100for various mission requirements were analyzed. For comparison, the samesimulated performances of a “ballonet” balloon system were alsoanalyzed. The “ballonet” system uses a super pressure balloon envelopefor lift. The inside of the super pressure lifting balloon includes asecond fully sealed balloon envelope, or ballonet. The ballonet ispressurized for descent and air is released form the ballonet fordescent. The performance of the LTA system 100 in comparison to theballonet system for three missions is described in this section.

1. 60,000-80,000 Feet

The first mission or simulation is a nominal altitude control range of20,000 ft, operating between 60,000 ft and 80,000 ft. This range andaltitude combination allows for access to a large variety of winddirections and speeds throughout much of the year. This type of variablewind access could allow for either a large degree of trajectory controlor the possibility of station keeping over certain areas of the globefor as long as days, weeks, and in some cases even months.

To allow for initial system sizing a payload mass of 128.4 kg wasassumed. This payload mass was determined by first sizing the LTA system100 with a total ZPB 200 suspended weight capability of 250 kg. The SPB300 envelope was sized with a maximum change in pressure (AP) capabilityof 3500 Pa at a volume of 1200 m³. The mass of this ballast envelope wasdetermined to be 121.6 kg leaving the remaining 128.4 kg for thepayload. This payload mass is assumed to include the mass of thecompressor/vent system, the power system, the flight avionics, and themission specific payload and instrumentation. The ballonet system doesnot require a tandem balloon so was sized to be able to lift the 128.4kg payload to the maximum float altitude with a maximum super pressurecapability of 1200 Pa. For this simulation the compressor 810 and powersubsystem was assumed to be the same for both systems in order to removeit as a variable and to force a closed design for the ballonet system.Accordingly, it was sized to deliver a maximum discharge pressure of3500 Pa at 350 liters/second at all the target altitudes. The ventarchitectures between the two systems, however, were sized differentlyto account for the large difference in the ballast balloon volumes. Forthe LTA system 100 architecture, a vent diameter of 50 mm was assumedand for the large ballonet architecture a vent diameter of 150 mm wasassumed. Table 2 summarizes the two system designs used for simulation#1.

TABLE 2 Simulation #1 altitude control system parameters of LTA system100 versus ballonet system. Parameter LTA System 100 Ballonet SystemMass of Helium at Launch (kg) 58 98 Mass of Helium Vented (kg) 5 0Volume of Lift Balloon (m3) 15052 10033 Mass of Lift Balloon (kg) 77 432Mass of Ballast Balloon (kg) 121.6 25 Payload Mass (kg) 128.4 128.4Total System Mass (kg) 327 585.4

The flight simulation for this first simulation was run for 96 hours andhad several different altitude inputs. Initially both systems were takento their maximum float altitude of 80,000 ft., and then altitude changeinputs were commanded as follows: Hour: 2, Altitude: 80,000 ft.; Hour:21, Altitude: 60,000 ft.; Hour: 30, Altitude: 80,000 ft.; Hour: 48,Altitude: 60,000 ft.; and Hour: 55, Altitude: 80,000 ft.

For the LTA system 100, only a low amount of free lift (5%) is requiredfor nominal flight operations. However 10% to 15% free lift may berequired to penetrate the cold temperatures of the troposphere andascend to the nominal float altitude. For the purposes of thissimulation the excess lift gas is being dumped passively by allowing theballoon system to ascend early in the flight when solar heating causesthe lift gas to expand the ZPB 200 envelope to its maximum designvolume. Gas that expands beyond this volume is vented from the ZPB 200by design. Because of its passive nature this is a conservative approachto venting the excess lift gas. However, in some embodiments, activelyopening a valve located near the top of the ZPB 200 may also accomplishthis task, thereby avoiding the early high altitude maneuver ifrequired. The ballonet approach also requires 10% to 15% free lift forinitial ascent, but all the lift gas is retained for nominal operation.

The performance summary for simulation #1 is shown in Table 3. Someconclusions that can be drawn from simulation #1 are that if the samecompressor characteristics are assumed for both systems, the LTA system100 architecture has more than double the descent rate of the ballonetsystem, while at the same time requiring less than half of thecumulative volume of atmospheric air to be pumped into the ballast tank,and therefore less than half of the total power usage. In addition, thesame LTA system 100 configuration can cover a total altitude range ofabout 65,000 ft., which is more than double that of the ballonet systemused in this simulation. The ballonet system, however, is more stable ata given altitude than is the LTA system 100 architecture, but alsorequires 68% more lift gas.

TABLE 3 Simulation #1 performance summary of LTA system 100 versusballonet system. Parameter LTA System 100 Ballonet System Maximum AscentRate (fph) 3300 3300 Maximum Descent Rate (fph) 5600 1700 AltitudeStability (+/−ft.) 450 50 Compressor Volume Pumped 9,200,000 19,200,000(liters) Compressor ON time (hrs.) 7.3 15.2 Energy (kW-h) 7.3 15.2 MaxAltitude Range (Δft) 65,000 30,000

In particular, the resulting analysis of simulation #1 showed that theLTA system 100 requires active control of the SPB 300 pressure over awider range of differential pressures during operations than theballonet system. This is required to both maintain altitude during solarfluctuations when the lift balloon increases and decreases in volume aswell as to actively change altitude when commanded. Additionally, toperform the proscribed maneuvers the LTA system 100 requires a higherdifferential pressure than the ballonet system because of thesignificantly smaller size of its ballast tank. The LTA system 100requires a maximum ΔP of 3500 Pa to perform rapid descents from 80,000ft. down to 60,000 ft., however most of the operational time the systemrequires less than 3000 Pa for operation. The ballonet in contrast onlyrequires a maximum ΔP of ˜500 Pa to perform operations, however itsoperational response time is much, much slower because of the length oftime necessary to transfer the amount of air required for altitudeadjustment into or out of the ballast tank. In other words, for thedescent maneuvers in particular, even though the ballast tank holds morepressure than is used, there is not enough time to add the additionalballast before the next ascent command is given. Ascent maneuvers alsotake place much more slowly with the ballonet system than the LTA system100 because so much more ballast must be vented to enable ascent.

The resulting analysis of simulation #1 also showed that, even with thecontinuous, small SPB 300 pressure adjustments required for stablealtitude retention, the LTA system 100 requires less than half of theoverall air volume to be pumped, as compared to the ballonet system,over the duration of the mission (9.2 million vs 19.2 million liters).This was also with significantly improved ascent and descent rates forthe LTA system 100. Less total pumped volume equates to less total‘pump-on’ time of the compressor 810 and therefore less overall powerrequired.

A final metric that can be pulled from the two designs compared in thissimulation is the maximum total altitude changes the systems, asdesigned, are capable of performing. This was done by iterating themission with lower and lower target altitudes until control authoritywas eventually lost. The LTA system 100 used for Simulation 1 is capableof descending in altitude to 20,000 ft. (total altitude changecapability of ˜65,000 ft) in comparison to the ballonet system which isonly capable of descent to 50,000 ft. (total altitude change capabilityof ˜30,000 ft). Because of the ballonet ballast tank total differentialpressure limitation of 1200 Pa, the ballonet system loses controlauthority over the altitude much earlier than does the LTA system 100.

2. 85,000-95,000 Feet

The second mission or simulation was developed to look at altitudecontrol system limitations for higher altitude use than that chosen forSimulation #1. Accordingly, a nominal range of 85,000 ft. to 95,000 ft.was chosen. The primary driver for this simulation was to determine anyperformance limitations when scaling the systems to allow for higheraltitudes and larger payloads versus the performance examined at themore favorable altitudes for station keeping and trajectory control usedin the first simulation. For the sake of comparability betweensimulations the same payload mass (128.4 kg) was used to size bothsystems for this simulation as was used in simulation #1. Additionally,the same power and compressor system, capable of delivering a maximumdischarge pressure of 3500 Pa at 350 l/s, was used and the ventarchitectures were sized for each system as with the simulation #1. TheZPB 200 envelope of the LTA system 100 was sized to have maximum volumeat 100,000 ft. to allow for the same high altitude excess free lift dumpmaneuver as was used early in the mission for simulation #1, however thesame simulation #1 ballast tank parameters were retained (3500 Pamaximum differential pressure at 1200 m³). The challenge for theballonet system was then to size it to be able to lift the 128.4 kgpayload to the maximum float altitude. This required a significantincrease in lift balloon size (from 10033 m³ to 43187 m³) whilesimultaneously keeping the overall mass as low as possible. This wasdone by reducing the material thickness as much as possible, howeverthis also resulted in a reduction of the maximum differential pressurecapability of the balloon from 1200 Pa to 900 Pa. Table 4 summarizes thetwo system designs used for simulation #2.

TABLE 4 Simulation #2 altitude control system parameters of LTA system100 versus ballonet system. Parameter LTA System 100 Ballonet SystemMass of Helium at Launch (kg) 70 132 Mass of Helium Vented (kg) 8 0Volume of Lift Balloon (m3) 29562 43187 Mass of Lift Balloon (kg) 138565 Mass of Ballast Balloon (kg) 121.6 65 Payload Mass (kg) 128.4 128.4Total Mass (kg) 388 758.4

The flight simulation for simulation #2 was run for 96 hours, as withsimulation #1, to compare the performance of both systems. Both systemswere initially commanded to the maximum float altitude and then werecommanded to follow a specific altitude profile as follows: Hour: 2,Altitude: 95,000 ft.; Hour: 21, Altitude: 85,000 ft.; Hour: 55,Altitude: 95,000 ft.; Hour: 72, Altitude: 85,000 ft.; Hour: 84,Altitude: 95,000 ft.

The performance summary for simulation #2 is shown in Table 5. ForSimulation #2, again with the same compressor characteristics used forboth systems, the LTA system 100 architecture demonstrated a much higherdescent rate than the ballonet system and still required less total‘pump on’ time and power usage. It must also be taken into account thatthe second altitude descent for the ballonet system was not fullycompleted in the time required, thus allowing for less ‘on time’ thanthe mission parameters nominally called for. Recall also that the designsolution for the ballonet system used for this simulation represents adesign solution that likely doesn't close because of its sheer size andcomplexity. Also, as noted in simulation #1, the stability of theballonet system is greater than that of the LTA system 100 system, whichis seen to become more unstable than observed at the lower altitudesimulation. Further, note that an extensibility comparison to examinethe maximum altitude change each system could achieve was not performedfor this simulation, but is addressed in simulation #3 which uses thesame general systems designs. This simulation #2 clearly demonstratesthat the ballonet system cannot adequately control altitude at highoperating altitudes. Attempts to increase the descent rate for theballonet system causes the design solution to diverge—the super pressureballoon size of the ballonet system and structural requirements growwith the larger compressor and power system mass, leading to a largersuper pressure balloon in the next iteration, and so on with increasingdivergence in each iteration.

TABLE 5 Simulation #2 performance summary of LTA system 100 versusballonet system. Parameter LTA System 100 Ballonet System Maximum AscentRate (fph) 5700 5600 Maximum Descent Rate (fph) 10000 600 AltitudeStability (+/−ft.) 150 50 Compressor Volume Pumped 32,600,000 34,500,000(liters) Compressor ON time (hrs.) 25.9 27.4 Energy (kW-h) 25.9 27.4 MaxAltitude Range (Δft) 75,000 17,500

In particular, the ballonet system is more stable at a given altitudethan is the LTA system 100, however the ballonet system also requiresmuch, much more time to respond to altitude adjustments. In particular,the maximum descent rate for the ballonet system was only about 600ft./hr., whereas the maximum descent rate for the LTA system 100 wasclose to 10,000 ft./hr., or about 16.5 times faster. Further, the LTAsystem 100 once again utilized its maximum ΔP of 3500 Pa, however theballonet system was only able to use 400 Pa of the 900 Pa limit becauseof the massive volume of the ballast tank in comparison to the volumeflow rate of the compressor 810. Also, the LTA system 100 requires fewertotal liters pumped (32,600,000 liters versus 34,500,000 liters),although at less of a difference than in simulation #1, but withsignificantly improved ascent and descent rates.

3. 85,000-95,000 Feet with Normalized Compressor

For simulations #1 and #2 above, a common compressor and power systemwas utilized in order to remove these as variables for the sake ofcomparison. However, the flow rate limitation of 350 liters/secondlimited the ascent and decent rate achievable by the ballonet system.Therefore, for simulation #3, the ballonet system from simulation #2 wasaltered to include a hypothetical 3,500 liter per second (lps)compressor (ignoring the volume, mass, and power requirements such a 10xsystem might have) in order to compare the LTA system 100 and ballonetsystem with more normalized or even performance characteristics. Theoriginal compressor assumptions were retained for the LTA system 100.Thus, the only change made between simulations #2 and #3 were to theassumed pump performance capabilities, and system parameters are thesame as shown in Table 5.

The results showed that the 10× enhanced compressor system used for theballonet system produced ascent and descent rates much closer to the LTAsystem 100 performance characteristics than simulations #1 and #2.However, as mentioned, the 10× compressor capability of the ballonet isunrealistic for practical implementation and is used for analysis only.With this enhancement came a substantially reduced ‘pump on’ time forthe ballonet system, however it had to move ten times the air in thattime period which still required more power than the same LTA system 100architecture as simulations #1, #2 and #3. Further, once again the LTAsystem 100 was able to demonstrate a substantially larger overallaltitude range than the equivalent ballonet system. However, theballonet system was again superior in its ability to hold a stablealtitude because of its constant overall volume.

In particular, for simulation #3 several conclusions can be drawn withregards to the use of the theoretical 3,500 lps pump system as part ofthe ballonet architecture. First, it performs extremely smoothly withaltitude ascents and descents that rival the LTA system 100 architecturewhile maintaining altitude consistently through diurnal cycling, as wasthe intent of this exercise. Second, the ballast tank pressure onlyincreases to 460 Pa. However, while the system performance is enhanced,it also requires more cumulative compressor air volume pumped over thecourse of the operational simulation than does the equivalent LTA system100 system, which equates to more power required. This is true despitethe fact that the actual “on” time for the ballonet pump is considerablyless (3.1 hrs) than for the LTA system 100 architecture (25.9 hrs).

Further, the same extensibility exercise was performed with simulation#3 as was undertaken for simulation #1. For each system the altitude wasiteratively decreased from the maximum float altitude until controlauthority was lost over the balloon and it was no longer able tofunction at the commanded altitude. The results showed that the LTAsystem 100 is capable of descending in altitude to 20,000 ft. for anoverall maximum altitude change capability of about 75,000 ft. Theballonet system, in comparison, is only capable of descent to 77,500feet, or a total altitude change of 17,500 ft. Below this altitude theballonet system lift balloon begins to hit its maximum pressurecapability and, in the simulation, lift gas is vented to prevent theballoon from bursting. With these observations it can be concluded thateven with an unrealistically enhanced compressor and power system thatwould allow it to match the performance characteristics of the LTAsystem 100 architecture at altitudes between 85,000 ft. and 95,000 ft.,the ballonet system can really only function reliably at or near themission specific altitudes that allow for taking full advantage ofvariable winds for steering.

4. Summary of Simulations #1, #2 and #3

Simulation #2 provides the clearest demonstration of the system levelimpact of controlling altitude at higher altitudes. As operatingaltitude requirements are elevated into the 29 km (95,000 ft.) altituderange, it becomes more difficult (energetically and mechanically) tochange altitude with a ballonet system because air densitylogarithmically decreases with altitude. This requires the ballonetcompressor to pump larger volumes of lower density air in order tocompress the lift gas as well as the ballast air into the one largesuper pressure balloon with an air ballonet. Sufficiently pressurizingthe large ballonet balloon to get useful descent rates of about 2 km/h(109 feet per minute) also imparts hoop-stress structural loads on thelarge super pressure ballonet balloon that significantly exceed currentdesigns and materials. Furthermore, once the ballonet system reaches thetarget operating altitude, it is trapped with no real ability todescend. Using the same compressor and power system, the LTA system 100has an average descent rate of 3.05 km/h (167 feet per minute) whereasthe ballonet system can only achieve 0.18 km/h (10 feet per minute).

Further, the use of a ballonet system for these missions is unrealisticas the design of a useful ballonet system operating at 29 km (95,000ft.) does not close. Achieving a useful descent rate requires acompressor capable of 10× the flow rate used in the example above. Sucha large compressor and power system for the ballonet system causes thesuper pressure balloon volume to grow dramatically at the high altitude,which drives up the compressor and power system mass as well as thehoop-stress in the super pressure balloon, further causing the design todiverge. By only actively compressing ballast air in a small separateballoon, as in the SPB 300 of the LTA system 100, the compressor 810 andpower system mass readily closes for the LTA system 100 altitude controlsystem.

Based on the comparative simulations performed in this study the LTAsystem 100 altitude control system is superior in three importantmetrics used to rate the performance of the two systems: Ascent/DescentRate, Altitude Range and Power Consumption. However, because of itsconstant volume architecture, the ballonet system has the advantage inaltitude stability.

In particular, the ascent/descent advantage goes to the LTA system 100architecture because it is a lower mass system and therefore requires acomparatively smaller ballast tank, i.e. the SPB 300, than the ballonetsystem. With existing, state of the art compressor technology the SPB300 of the LTA system 100 can simply be pressurized at a faster rate. Assimulation #3 demonstrated, even with the ballonet system having acompressor flow rate at ten times that of the LTA system 100 compressor810, the ascent and descent rates of the ballonet system were still lessthan the LTA system 100 architecture.

The altitude range advantage also goes to the LTA system 100architecture because it has a lower overall system mass and is thereforemore greatly affected by the ballast in the SPB 300. The SPB 300 volumeis also not structurally tied to the ZPB 200 lifting balloon and cantherefore be designed to any volume necessary to accomplish missionparameters. On the other hand, because it is so structurally tied to themechanical properties of its super pressure lift balloon, the ballonetsystem can only accept so much volume increase before it challenges thestructural integrity of the lift balloon envelope. The ballonet systemarchitecture does not close for useful altitude control rates operatingnear the 29 km (95,000 ft.) altitude range.

Further, because the SPB 300 of the LTA system 100 can pressurize anddepressurize much more quickly than the ballonet ballast tank, the LTAsystem 100 architecture also has the advantage in terms of overall powerusage for the same mission parameters at lower altitudes.

However, the results also showed that the LTA system 100 architecturedoes fall short of the ballonet system performance in terms of altitudestability. Because the ZPB 200 required for the LTA system 100architecture changes volume in response to the ever changing solarheating cycle, the pressure of the SPB 300 must be continually adjustedin order to hold altitude. In contrast, the ballonet system for liftuses a super pressure balloon, which is not subjected to volume changedue to solar heating and cooling. Even with the constant, smallcompressor inputs required by the LTA system 100 for altitude stability,however, it has been shown that the LTA system 100 architecture requiresless power than the ballonet approach. However, due to the wind analysesperformed it was determined that the stability of the LTA system 100system met the requirements of the system to remain within a particularwind layer.

N. Continuous Multi-Chamber Super Pressure Balloon

The various LTA systems and other features described herein may use oneor more of various embodiments of a multi-chamber super pressure balloon(SPB). The multi-chamber SPB may be a continuous multi-chamber SPB, asfurther described. Such balloon systems are sometimes referred to asVariable Altitude Air Ballast Balloon Systems (VAABBS). Some exampleembodiments have been described above, for example, with respect toFIGS. 9C-9E. Described herein are further non-limiting examples ofdesigns, systems and methods for multi-chamber SPB's, such asconfigurations, methods for constructing and using multi-chamber SPB's,and other features.

The various embodiments of the multi-chamber SPB described herein may beused with any of the systems, devices or methods shown in and/ordescribed with respect to FIGS. 1-12B, and vice versa. For example,various embodiments of the multi-chamber SPB may be used with the LTAsystems 100, 101, 102, 103 or 104, and vice versa.

FIGS. 13A-13C depict LTA systems having an SPB 300 with one or morechambers. FIG. 13D depicts an SPB 305′ having five chambers, which maybe used with an LTA system or by itself. These are example applicationsof continuous multi-chamber SPB's, which may be pumpkin-shaped as shown,air ballast tanks for the Variable Altitude Air Ballast Balloon System(VAABBS) with the Zero Pressure balloon (ZPB) 200 providing lift and apayload supported below the SPB 300. The payload for the LTA systems106A, 106B, 106C may be part of the stratocraft 400, as described above.

A multi-chamber SPB 300 may scale optimized pressure vessels, such assuper pressure (SP) vessels, to effect desired changes in altitude ofLTA systems across a large range of altitudes. The following embodimentsor examples show various arrangements, features, etc. of someembodiments of the multi-chamber SPB 300. Some examples show SPBchambers 300A, 300B, 300C fluidly connected to each other establishinglarge volumes in which a Differential Pressure (DP) can be achievedthrough pumping ambient or stored air with a compressor. Multi stagecompressors, such as those described herein, may also be utilized toachieve higher DP.

The multi-chamber SPB may include various advantageous features. Forexample, waist fittings, inner bladders, skin film additives protectingagainst Ultra Violet radiation, high density light weight batteries, andother features may be implemented. These and other advantageous featuresmay be used in the various multi-chamber SPB's described herein toachieve superior results. For instance, various new demands ofstratospheric capable platforms, in general a multitude of BalloonControl Methods and stratospheric balloon configurations, are feasible.The following describes some embodiments and discusses some of therelative merits of each, including for example in the areas of flightperformance, launch methods and manufacturing.

In some embodiments, multiple chambers of an SPB 300 may be used insteadof attempting to build a single larger SPB that may be limited by limitsof materials and technology. A “chamber” may refer to a singlecompartment of a continuous multi-chamber SPB. “Chamber” may also referto a single SPB fluidly separated from one or more other SPB's.Multi-chamber SPB's may allow for more easily staying within the limitsof the various materials due to the smaller size of each chamberrelative to an equivalent larger, single chamber SPB. Two or morechambers may allow for a fixed performance that scales linearly aschambers are added. Multi-chamber SPB's may carry lift gas (e.g. Heliumor Hydrogen), a mix of lift gas and ballast gas (e.g. air), or justballast gas, as further described. A multi-chamber SPB may be pairedwith a lift gas-filled Zero Pressure Balloon (ZPB) that can be separatefrom or fluidly connected with the SPB.

FIG. 13A is a side view of an embodiment of an LTA system 106A with anSPB 300 having a single SPB chamber 300A. FIG. 13B is a side view of anembodiment of an LTA system 106B with a two-chambered SPB 300 having afirst SPB chamber 300A and a second SPB chamber 300B. FIG. 13C is a sideview of an embodiment of an LTA system 106C with a three-chambered SPB300 having a first SPB chamber 300A, a second SPB chamber 300B, and athird SPB chamber 300C. In some embodiments, the SPB 300 may have four,five, six, seven, eight, nine, ten or more chambers.

The SPB chambers 300A, 300B, 300C may have the same or similar featuresand/or functionalities as other SPB's and/or chambers described herein,for example shown in and described with respect to FIGS. 1, 3A-4B, and9A-12B, and vice versa. The chambers 300A, 300B and/or 300C may bealigned axially as shown, which may be referred to as a “tandem”configuration. In some embodiments, one or more chambers may beconfigured laterally, as further described. The chambers may be formedfrom continuous gores, as further described. For example, the SPBchambers 300A and 300B in FIG. 13B may be formed from continuous goresthat extend from an upper portion, for example a top or apex of chamber300A, to a lower portion, for example a bottom or nadir, of chamber300B. For example, the SPB chambers 300A, 300B and 300C in FIG. 13C maybe formed from continuous gores that extend from an apex of chamber 300Ato a nadir of chamber 300C. More than three chambers may be formed inthis manner. Further, the multi-chamber SPB 300 may be supplied withambient air via one or more compressors, such as the compressor 810and/or compressor assembly 810 described herein. The compressor(s) maybe located with the payload support 700, as described herein, and befluidly connected with one or more of the chambers of the SPB 300.

In some embodiments, the chambers 300A, 300B and/or 300C may be modularsuch that one or more chambers may be added to and/or removed from anexisting LTA system. For example, the SPB chamber 300B may be added tothe LTA system 106A to form the LTA system 106B. For example, the SPBchamber 300C may be added to the LTA system 106B to form the LTA system106C. More modular chambers may be added in this manner. In someembodiments, chambers may be manufactured with connector fittingsconfigured to attach to other connector fittings in order to modularlystack the chambers. For example, “middle” chambers, chambers not locatedon the top or bottom ends of the multi-chamber SPB, may be outfittedwith top and bottom connector fittings configured to attach to anadjacent connector fitting. “End” chambers, on the top and/or bottom endof the multi-chamber SPB, may be outfitted with one end having aconnector fitting and the opposite end having an end fitting. Thus, twoend chambers and one or more middle chambers may be assembled as neededfor a particular mission. The end chambers may be flipped around toserve as top or bottom chambers as needed. In some embodiments, maleconnector fittings threadingly engage with female connector fittings. Insome embodiments, connector fittings are connected together withfasteners, seals, etc.

The SPB 300 may include one or more rings or waist fittings 305B. Thewaist fitting 305B may be located at or near a waist 311A (see, forexample, FIG. 14D) of the SPB 300. The waist 311A may be a portion ofthe gores 325A, skin and/or other features of the SPB 300 that islocated between two adjacent chambers of the SPB 300. As shown in FIG.13B, the waist 311A may be located between the SPB chamber 300A and thechamber 300B. There may be multiple waists 311A for a single SPB 300. Asshown in FIG. 13C, a first waist 311A may be located between the SPBchamber 300A and the chamber 300B, and a second waist 311A may belocated between the SPB chamber 300B and the chamber 300C. The waist311A may be a location of minimum width of the SPB 300. The waist 311Amay have a diameter that is smaller than the diameter of adjacentportions of the SPB 300. The waist 311A may be a “thinner” portion orportions of the SPB 300. The waist 311A is described in further detailherein, for example with respect to FIG. 14D.

The waist fitting 305B may have the same or similar features and orfunctionalities as the fittings described herein, for example thefitting 305A and/or the various fittings described in the section“BALLOON FITTINGS”, and vice versa. The fitting 305B may be a structuralelement circumferentially surrounding the waist of the SPB 300 toprovide structural support and allow fluid to flow between the variouschambers 300A, 300B and/or 300C, as further described. The fitting 305Bmay be a circumferential constriction of the SPB. The fitting 305B mayinclude a ring body extending circumferentially about a central axis anddefining an opening therethrough along the axis, the fitting configuredto be positioned around the waist 311A with the continuous envelope(e.g. gores 325A, etc.) extending through the opening of the fitting305B.

Such multi-chamber SPB's 300 as in LTA system 106B and 106C mayfacilitate achievement of advanced performance targets. For example, toreach design goals such as with the VAABBS, described for example inU.S. Pat. No. 9,540,091, titled “HIGH ALTITUDE BALLOON SYSTEMS ANDMETHODS” and issued Jan. 10, 2017, the entirety of which is incorporatedherein by reference, as the system gets larger there may not be asingular pumpkin ballast balloon that achieves the desired performancetargets without either reaching a strength limitation or a stabilitylimitation (e.g., s-clefting). When that limitation is reached, onedesign choice is to turn to stacking (or otherwise arranging) multiplepumpkin balloons or balloon sections such as chambers. A single sizepumpkin may structurally deform, for example by s-clefting, whereas thesmaller chamber design prevents or at least mitigates the risk of suchdeformations, failures, etc. A continuous multi-chamber design andconstruction method may be efficient mass-wise and for manufacturing,among other advantages.

The two-chamber SPB 300 of LTA system 106B may allow for a heavierpayload that fits in the stratocraft 400, or instead it may allow theLTA system 106B to be more responsive in its altitude changingperformance. The three-chamber SPB 300 of LTA system 106C (which maystill use the same compressor as the 2-chamber version) may permitconfiguration for a larger payload carried by the stratocraft 400.

In some embodiments, there may be four or more chambers. For example,FIG. 13D is a perspective view of an embodiment of a five-chambered SPB305′. The SPB 305′ may include the same or similar features and/orfunctionalities as other SPB's described herein, and vice versa. The SPB305′ may include first through fifth chambers 300A, 300B, 300C, 300D,and 300E. The chambers 300A, 300B, 300C, 300D, and 300E may include thesame or similar features and/or functionalities as other chambersdescribed herein, and vice versa. In some embodiments, the SPB 305′ mayinclude fewer or greater than five chambers. The chambers may bepositioned axially. Waist fittings 305B may be included at the waistportions of the SPB 305′ located between adjacent chambers, for examplebetween chamber 300A and 300B, etc. As shown, there are four waistsections each having the waist fitting 305B. There may be a base 359,which may be an end fitting as described herein. In some embodiments,there may be one or more interface fittings 358 at upper or lowerportions of one or more of the chambers. The chambers may be individual,fluidly separate and distinct pumpkins joined at common interfacefittings 358. In some embodiments, some or all of the chambers may befluidly connected. An interior volume 357 may extend throughout thelength of the SPB 305′ into each chamber. The volume 357 may instead bea separate compartment within each chamber. Gores 325A may extend alongone or more of the chambers. The gores 325A may extend along an entirelength of the SPB 305′, such as from the first chamber 300A to the fifthchamber 300E. The gores 325A may be formed of smaller length subunitsthat form the larger gores 325A.

The various embodiments of the SPB's having multiple chambers mayinclude chambers with a variety of sizes, shapes and configurations. Forinstance, there may be many smaller-sized chambers attached together, inseries, parallel, other configurations, or combinations thereof. Forexample, there may be two, three, four, five, six, seven, eight, nine,ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen,eighteen, nineteen, twenty, thirty, fifty, one hundred, or any othernumber of chambers. For example, the chambers may have maximum widthswhen inflated in the range from about two feet to about two hundredfeet, from about five feet to about one hundred fifty feet, from aboutten feet to about one hundred feet, from about fifteen feet to aboutseventy five feet, from about twenty feet to about fifty feet, or otherranges or sizes.

In some embodiments, multiple chambers may be provided with pressurizedair via a single compressor inlet or valve in one or more of thechambers. In some embodiments, a tube may extend from the compressorthrough each of the chambers, for example axially through the chambers.The tube may have openings at or near each chamber to providepressurized air directly to each chamber. In some embodiments, eachchamber or groups of multiple chambers may be fluidly separated from oneor more other chambers, for example to mitigate the risk of puncture orotherwise failure of one or more of the chambers to perform its functionas securing pressurized air therein. For example, a tube may extend froma compressor to each chamber and have ports along the tube to providepressurized air to one or more chambers. The tube ports may includevalves. The chambers may include valves located between adjacentchambers to control the movement of pressurized air between thechambers. For example, if one chamber is punctured or otherwise fails,that chamber, or a group of chambers including that chamber, may besealed off from the other chambers to isolate the malfunction and allowthe other chambers to successfully operate. The chamber or group ofchambers may be sealed off with valves, with fluidly separated chamberssuch as with a barrier, etc. The valves or barriers may be located atone or more waists formed by the multiple chambers.

In some embodiments, the multi-chamber SPB 300 may include one or moresections that provide a “sausage-like” configuration to the SPB at leastwhen inflated. The SPB 300 may include a continuous envelope, e.g.formed from gores 325A and/other features. The continuous envelope maybe “continuous” as described herein, for example extending substantiallyuninterrupted along its length. The continuous envelope may include afirst section such as the first chamber 300A, a second section such asthe second chamber 300B, and a third section such as the waist 311A. Thefirst, second and third sections may be configured to extend axiallyalong a central axis with the third section located between the firstand second sections, and the third section having a smaller maximuminflated width than each of the first and second sections. Acircumferential constriction such as the waist fitting 305B may beincluded that is configured to extend around the continuous envelopebetween the first and second sections. A plurality of tendons 330A, 300Bmay be configured to extend from the circumferential constriction andaround the continuous envelope to bias the first and second sectionsinto respective first and second pumpkin shapes when the continuousenvelope is inflated. In some embodiments, there may be four or morewider sections, two or more thinner sections, two or more constrictions,etc.

The sections, e.g. the chambers 300A, 300B, 300C, may have variousgeometries. An aspect ratio of one or more of the sections may bedefined as the ratio of the maximum width to maximum height of thesection when inflated. The aspect ratio may be from about 0.25 to aboutten, from about 0.5 to about five, from about one to about four, fromabout two to about three, about one, about two, about three, about four,about five, one, two, three, four, five, or any other smaller or largerrange or amount. Thus the particular shapes and configurations for themulti-chamber SPB's shown and described in detail herein are examplesonly, and many other geometries may be implemented that are within thescope of the description.

FIG. 14A is a side view of the two-chambered SPB 300 of the LTA system106B. FIG. 14B is a side view of the three-chambered SPB 300 of the LTAsystem 106C. FIG. 14C is an embodiment of a gore 325A, shown in a flatconfiguration, from the two-chambered SPB 300 of the LTA system 106B.

As shown in FIG. 14A, the SPB chamber 300A may include an upper portion310A and a lower portion 315A. The SPB chamber 300B may include an upperportion 310B and a lower portion 315B. The upper portions 310A, 310B andlower portions 315A, 315B may have the same features and/orfunctionalities as respectively the upper portion 310 and lower portion315 described herein. The SPB 300 may include a plurality of tendons330A and 300B, gores 325A, and bulges 340A and 340B. The tendons 330Aand 300B, gores 325A, and bulges 340A and 340B may have the same orsimilar features and/or functionalities as other tendons, gores andbulges described herein, such as respectively the tendons 300, gores325, and bulges 340, and vice versa.

The gores 325A may extend downward from the upper portion 310A. Forexample, the gores 325A may extend downward from an apex of the SPBchamber 300A. The gores 325A may extend downward from an apex fitting314A. The gores 325A may extend continuously from the upper portion 310Aof the first SPB chamber 300A to the lower portion 315B of the secondSPB chamber 300B. For example, the gores 325A may extend to a nadirfitting 314B. The gores 325A may extend from the upper portion 310A,through the fitting 305B at the waist 311A, and to the lower portion315B. It is understood that “extending from” is not meant to imply adirection but rather that the gores 325A extend between and/or to theaforementioned locations.

The tendons 330A may extend downward from the upper portion 310A. Thetendons 330A may extend downward from an apex of the SPB chamber 300A.The tendons 330A may extend downward from an apex fitting 314A. Thetendons 300A may extend to the lower portion 315A. The tendons 300A mayextend to the waist fitting 305B located at the waist of the SPB 300.The tendons 330A may terminate at the fitting 305B. In some embodiments,one, some or all of the tendons 300A may continue downward from thefitting 305B to the SPB chamber 300B, for example to the lower portion315B, nadir, and/or nadir fitting 314B of the SPB chamber 300B.

The tendons 330B may extend upward from the lower portion 315B. Thetendons 330B may extend upward from the nadir of the SPB chamber 300B.The tendons 330B may extend upward from the nadir fitting 314B. Thetendons 300B may extend to the upper portion 310B. The tendons 300B mayextend to the waist fitting 305B located at the waist of the SPB 300.The tendons 330B may terminate at the fitting 305B. In some embodiments,one, some or all of the tendons 300B may continue upward from thefitting 305B to the SPB chamber 300A, for example to the upper portion310A, to the apex of the chamber 300A, and/or to the apex fitting 314A.As shown, the tendons 330A extend between the apex fitting 314A and thefitting 305B, and the tendons 330B extend between the nadir fitting 314Band the fitting 305B.

The fittings 314A and 314B may be located respectively on the top andbottom of the multi-chambered SPB. The apex fitting 314A and/or thenadir fitting 314B may have the same or similar features and/orfunctionalities as other fittings described herein, such as the apex 313described herein for example with respect to FIG. 4B-4C, and/or theinterface 1700 or fitting assembly 1801, 1802 described herein forexample with respect to FIGS. 19A-19E.

The waist fitting 305B may be located between the chamber 300A and 300B.An example single chamber SPB may have an inflated volume of 1,803 cubicmeters and have the same maximum tendon tension load of 1,520 lbs at3,500 Pascal differential pressure (DP). For an equivalent multi-chamberSPB 300, an efficient example for the performance figure of meritR=(DP×Volume/Gross mass) may be with a fitting 305B having a radius of4.0 meters or about 4.0 meters.

The width of the waist of the multi-chamber SPB 300 may be referred toas a junction diameter. The junction diameter between the two (or more)merged chambers is a variable that can be experimented with until theperformance ratio R={Differential Pressure×Tank Volume/Gross dry mass}is maximized or otherwise optimized. In some cases, the performanceratio is maximized when the junction diameter is from about 35-55%, fromabout 40-50%, at about 46%, or 46% of the maximum chamber diameter. Thefitting 305B experiences a large tensile force. In some embodiments, thefitting 305B experiences about 54,530 lbs of tensile force. In someembodiments, the fitting 305B may be a rope ring that is sized forDyneema (ultra-high molecular weight polyethylene) rope that is about4,596,000 denier (˜1″ diameter rope, 12.8 kg). This may be theequivalent of using 29× 3/16″ diameter Dyneema cords.

In some embodiments, the waist fitting 305B is a structural fitting,such as a structural ring or rings. Such fitting may take advantage ofthe continuous gores 325A to use a modified end fitting in place of forexample, a rope ring or rope belt, to constrain the junction or waistbetween the chambers. The radius of a structural fitting 305B may beconsiderably smaller than that which would be applicable using the ropering or rope belt method. Such structural fitting 305B may constrain thejunction of the super pressure pumpkin balloons at the point where the“hour glass” shape is created by closely tailoring gores. Furthermorethe structural fitting 305B would be retained in place using the tendons330A, 330B from the upper and lower chambers 300A, 300B. This exampleconfiguration can also be constructed as a single structure by heatsealing the gore pattern continuously at the juncture where the fitting305B would constrict the shape, producing an hour-glass shaped gorepattern.

As shown in FIG. 14B, the SPB 300 includes the plurality of tendons 330Aand 300B as well as tendons 300C, the gores 325A, and the bulges 340Aand 340B as well as bulges 340C. The tendons 330C and bulges 340C may beused on the chamber 300C. The tendons 330C and bulges 340C may have thesame or similar features and/or functionalities as other tendons andbulges described herein, such as respectively the tendons 300, 330A,330B and the bulges 340, 340A, 340B, and vice versa.

The tendons 330C may extend upward from the nadir of the SPB chamber300C. The tendons 330C may extend upward from the nadir fitting 314Cwhich in the three-chambered SPB 300 is located on the nadir of thechamber 300C. The tendons 300C may extend from the nadir of the chamber300C to the waist fitting 305B located at the lower waist of the SPB300. The tendons 330C may terminate at the fitting 305B. In someembodiments, one, some or all of the tendons 300C may continue upwardfrom the fitting 305B to the upper fitting 305B and/or to the apex ofthe chamber 300A, for example to the apex fitting 314A. As shown, thetendons 330A extend over the chamber 300A between the apex fitting 314Aand the upper fitting 305B, the tendons 330B extend over the chamber300B between the upper fitting 305B and the lower fitting 305B, and thetendons 330C extend over the chamber 300C between the lower fitting 305Band the nadir fitting 314B. The various tendons 330A, 330B, 330C of thetwo- and three-chambered SPB's 300 bias the skin of the respectivechambers into a pumpkin shape, as described herein.

As shown in FIG. 14C, the gore 325A from the two-chambered SPB 300 ofFIG. 14A is shown in a flat configuration. The gore 325A has a first end326A and extends to a second end 326B. The first end 325A may be locatedat or near an upper portion, such as the apex or top, of the chamber300A when assembled with the multi-chambered SPB 300. The second end325B may be located at or near a lower portion, such as the nadir orbottom, of the chamber 300B when the gore 325A is assembled with themulti-chambered SPB 300.

The gore 325A includes a first wide portion 327 on the same end as thefirst end 326A and a second wide portion 329 on the same end as thesecond end 326B. The first and second wide portions 327, 328 increase inwidth from their respective ends and then decrease in width toward acenter portion 328. The center portion 328 may be a thinner portion ofthe gore 325A. When the gore 325A is assembled with the multi-chamberedSPB 300, the center portion 328 may be located at or near the waist ofthe multi-chambered SPB 300, the first wide portion 327 may be locatedat the first chamber 300A, and the second wide portion 329 may belocated at the second chamber 300B. The middle portion 328 may belocated at or near the halfway point between the first and second ends326A, 326B, for example with a multi-chambered SPB 300 that is symmetricor approximately symmetric about a plane that intersects the waistand/or the waist fitting 305B (e.g. horizontal as oriented in the figureand at the waist fitting 305B).

In some embodiments, the middle portion 328 may not be located at ornear the halfway point between the first and second ends 326A, 326B, forexample with a multi-chambered SPB 300 that lacks the symmetry asdescribed. For example, the chamber 305B may be larger than the chamber305A, or vice versa.

The gore 325A may be continuous from the first end 326A to the secondend 326B to at least partially form a continuous envelope. “Continuous”as used here may refer to a single piece of material that forms theentire gore 325A, or it may refer to multiple pieces of materialconnected together to form the gore 325A. The gore 325A may extendcontinuously from the lower portion, such as the nadir or bottom, of theSPB 300 for example from the nadir fitting 314B, to the upper portion,such as an apex or top, of the SPB 300 for example to the apex fitting314B. The gore 325A, such as the center portion 328, may extend axiallyor generally axially at a location that is radially inward of thefitting 305B, such as through an inner opening defined by the fitting305B. In some embodiments, the gores 325A may extend axially and throughthe fitting 305B. The gore 325A may extend from near the lower portionto the upper portion, such as when an annular piece and/or end fittingis used at the apex and nadir, as described herein.

The gores 325A may therefore form the chamber 300A and the chamber 300B.Multiple gores 325A may be assembled together, e.g. heat-sealed, suchthat adjacent edges of the first wide portions 327 are assembledtogether to form the chamber 300A, adjacent edges of the center portions328 are assembled together to form the waist, and adjacent edges of thesecond wide portions 329 are assembled together to form the chamber300B.

In some embodiments, the gore 325A may be separate portions that areconnected to the waist fitting 305B and at the respective apex and nadirof the SPB 300. For example, the gore 325A may comprise first and secondseparate pieces that are connected at respective locations to form thechambers 300A, 300B.

The gore 325A may be used to form the two or three-chamber SPB 300 aswell as SPB's with four or more chambers. A corresponding number of thewide portions 327, 329 and center portion(s) 328 may be incorporated forsuch multi-chamber SPB's. For example, a three-chamber SPB 300 may beformed with the gore 325A having three wide portions and a thinnercenter portion between the first and second wide portion and between thesecond and third wide portion. The three wide portions may form thechambers 300A, 300B, 300C and the two wide portions may form the twowaists 311A Thus the design can be scaled to accommodate SPB's withthree, four or more chambers.

The continuous gore 325A design provides many advantages. For example,it may eliminate the need for attachments of the gores between thechambers 300A, 300B, 300C. Space and weight may be saved to allow foruse of the waist fitting 305B instead. The manufacturing may be easieras the continuous multi-chamber pumpkin SPB 300 is made as one assemblyinstead of multiple independent balloons that then have to be connectedtogether for example with interface fittings. There may be a greatervolume to mass ratio as compared to connecting independent pumpkins, forexample maximizing or optimizing at a 46% neck as described. It may alsoallow for larger volumes for the air ballast tank, which may give betteraltitude performance, while avoiding structural deformations such asglobal shape instability, e.g. s-clefting.

FIG. 14D is a cross-section view of the two-chambered SPB 300 of the LTAsystem 106B taken along the lines 14D-14D as indicated in FIG. 14A. Theapex and nadir fittings 314A, 314 b are removed for clarity. An SPB 300with three or more chambers may include the same or similar featuresand/or functionalities as described with respect to the cross-sectionalview of the two-chambered SPB 300 of FIG. 14D.

As shown in FIG. 14D, the SPB 300 has a waist 311A. The various waistsdescribed herein for multi-chamber SPB's may have the same or similarfeatures and/or functionalities as the waist 311A, and vice versa. Thewaist 311A is located between the upper chamber 300A and the lowerchamber 300B. The waist 311A may be located halfway or about halfwayaxially between a top 312A and a bottom 317A of the SPB 300, and/orbetween an apex 313 and a nadir 313B of the SPB 300. In someembodiments, the waist 311A may be located more or less than halfwaybetween the top 312A and the bottom 317A of the SPB 300 and/or more orless than halfway between the apex 313 and the nadir 313B of the SPB300. The top 312A and the bottom 317A may have the same or similarfeatures and/or functionalities as respectively the top 312 and thebottom 317 described herein, and vice versa. The apex 313 may be asdescribed herein, for example with respect to FIG. 4B. The nadir 313Bmay have the same or similar features and/or functionalities asrespectively the nadir described herein, for example with respect toFIG. 3A, and vice versa.

The waist 311A may be formed by the gores 325A that form the chambers300A, 300B. The waist 311A may be a location of minimum width, e.g.diameter, of the SPB 300. The waist 311A may inflate to have an inflatedwaist width that is smaller than the maximum inflated widths of one ormore, or each, of the adjacent two chambers 300A, 300B. The inflatedwaist width may be a minimum width of the portion of the continuousenvelope that includes the waist 311A. The widths of the chambers andwaist(s) 311A may be measured approximately horizontal as oriented inFIG. 14D. The widths of the chambers and waist(s) 311A may be measuredperpendicularly to the central axis of the system, such as the axis 105(see, e.g., FIGS. 9C-9E). These maximum widths may be locatedapproximately halfway along an axial length of the respective chamber orwaist, or in other locations. The waist 311A may be an inflection pointof the envelope formed by the gores 325A. For example, along an axialdirection, the envelope at the waist 311A may extend radially inwardtoward the central axis and then extend radially outward away from theaxis. The waist 311A may form a sharp or rounded inner projection of theSPB 300. The waist 311A may have a number of other configurations, suchas circular, rounded, segmented, other shapes, or combinations thereof.

The waist 311A may include adjacent portions of the upper and lowerchambers 300A, 300B. In some embodiments, the waist 311A may bereinforced, for example with additional gore material, fabric, thickerskin section, fittings, protective coatings or materials, other suitablefeatures, or combinations thereof. In some embodiments, the waist 311Amay include such features to accommodate receiving the waist fitting305B thereon. The waist fitting 305B may be placed over the end of theuninflated or partially inflated SPB 300 and be located at the waist311A of the SPB 300. The SPB 300 may then be fully or more inflated tosecure the waist fitting 305B at the waist 311A. The waist 311A may ormay not contact an inner side of the fitting 305B. The waist 311A maycontact upper and lower portions of the fitting 305B, for example wherethe upper and lower chambers 305A, 305B extend over the fitting 305B andcontact it on upper and lower sides of the fitting 305B. The fitting305B provides a structural support and reinforcement for the SPB 300 byreceiving and supporting the outward forces of the balloon skin envelopedue to inflation of the SPB 300.

The SPB 300 includes a first interior volume 316A inside the firstchamber 300A. The SPB includes a second interior volume 316B inside thesecond chamber 300B. The volumes 316A, 316B may be interior spacesconfigured to receive air and/or other gases therein. The volumes 316A,316B may be in fluid communication with each other, such that fluid forexample air may freely travel between the volumes 316A, 316B. Thevolumes 316A, 316B may be fluidly connected between the waist 311A. Thisarea may be open as shown. Thus volumes 316A and 316B may be portions orareas of the same single large interior volume of the SPB 300. In someembodiments, the volumes 316A, 316B may be connected by a fluidconnection such as a conduit etc. at this location, as further describedherein for example with respect to FIGS. 15D-15E. In some embodiments,the volumes 316A, 316B may be fluidly separated for example with abarrier or valve cutoff in a fluid connection, as further described.

FIGS. 15A-15E depict various embodiments of multi-chamber SPB's havingvarious embodiments of a barrier. FIGS. 15A and 15B are cross-sectionviews of an embodiment of a two-chambered SPB 300 having a barrier 350shown in two different configurations. FIG. 15C is a cross-section viewof an embodiment of a three-chambered SPB 300 having a barrier 351.FIGS. 15D and 15E are cross-section views of an embodiment of atwo-chambered SPB 304 having the barrier 350.

The various configurations with the barrier 350 may be used as aregenerative air ballast system. The system and related methods mayinclude a continuous multi-chambered SPB with the barrier 350 forming aninternal air ballast bladder. In some embodiments, there are may bemultiple, e.g. two, super pressure ballonets utilizing a singlecompressor. The systems and methods described herein allow for greaterair ballast mass achieved without violating the largest possiblediameter (and thus hoop stress of mass optimized balloon material) of anSPB ballonet.

In some embodiments, the high altitude balloon systems can include asingle envelope with a “sausage” configuration and venting to adjust airpressure for buoyancy. The balloon can also be a series of ballonets(balloons with internal bladders that fluidly couple to ambient air)arranged in a constellation. This may allow a higher differentialpressure to be realized for the given volume without incurring thes-cleft global shape instability. Some embodiments may also include ablimp or ballonet configuration. In this configuration a flexiblebladder or barrier may freely expand and contract with changes inpressure.

As shown in FIGS. 15A and 15B, the SPB 302 may include the chambers 300Aand 300B with the waist 311A. The SPB 302 may include the same orsimilar features and/or functionalities as the other SPB's describedherein, such as the SPB 300, 301, etc., and vice versa. The SPB 302includes the barrier 350. The barrier 350 may be a flexible innerseparator located within the SPB 302. The barrier 350 may be elastic. Insome embodiments, the barrier 350 may stretchable to accommodate higherpressures. With increasing pressure, the barrier 350 may expand orstretch, and then with decreasing pressure the barrier 350 may contract.The barrier 350 may be formed from the same or similar materials as theskin of the SPB 302. The barrier 350 may be formed from differentmaterials as the skin of the SPB 302. The barrier 350 may connect at orapproximately at an inner side of the waist 311A, as shown. The barrier350 may connect circumferentially around the inner side of the waist311. In some embodiments, the barrier 350 may connect in other places,such as within one or both of the chambers 300A, 300B. The barrier 350may be a flat or generally flat material configured to conform to thesurfaces to which it is to be attached within the SPB 302. In someembodiments, the barrier 350 is formed with gores or other portions tocause the barrier 350 to take the general shape of a bag. The barrier350 may be flexible such that changing pressures on either side of thebarrier 350, or a pressure differential, will cause the barrier tochange configurations. The barrier 350 may be an open configuration asshown, such as a layer. The barrier 350 may include one or more layers.There may be one or more barriers 350. In some embodiments, the barrier350 may form a closed shape, as further described herein.

The barrier 350 provides a fluid barrier within the SPB 302. The barrier350 thus prevents or reduces the flow of fluid such as air through thebarrier 350. The barrier 350 may be sealingly connected along the edgeto the inner surface of the SPB 302 and therefore separate the innervolume of the SPB 302 into two fluidly separate inner compartments. Asshown, the barrier 350 may separate the SPB 302 into a first compartment352 and a second compartment 354. The compartments 352, 354 may befluidly separated by the barrier 350. The first compartment 352 mayinclude compressed lift gas. The second compartment 354 may includecompressed ballast air.

The SPB 302 may take in or expel external ambient air to add or removeballast air. A compressor 356 may be used to provide or remove air tothe SPB 302. The compressor 356 may be similar to the compressorsdescribed herein. The compressor 356 may be located at or near the lowerend of the SPB 302 as shown. In some embodiments, the compressor 356 maybe included with the stratocraft 400 as described herein and be fluidlyconnected with the compartment 354 via a hose or tube. The compressor356 may provide pressurized air into the compartment 354. The increasingpressure in the compartment 354 may cause the barrier 350 to move upwardas oriented. The SPB 302 is shown in a first configuration in FIG. 15Aand a second configuration in FIG. 15B. The barrier 350 may be in aloose configuration in FIG. 15A, and be biased toward the configurationof FIG. 15B due to the intake of pressurized air into the compartment354.

FIG. 15B shows the barrier 350 located within the chamber 300A. Thecompartment 354 may be pressurized to cause the barrier 350 to take thisor other configurations. The pressure of ballast air in the compartment354 may exceed the pressure of the lift gas within the compartment 352.This may accumulate ballast in the form of compressed atmospheric gases.Such mass accumulation increases system density and contributes todescent of the LTA system.

The barrier 350 in turn expands and by doing so decreases the volume ofthe compartment 352 in which lift gases reside. The change in volume ofthe compartment 352 of the structure results in pressurization of thelift gas removing part of its capacity to provide free lift to theentire system. The overall effect of the compressor 356 acting onatmospheric gases and pressurizing the compartment 354 is to affect amass change of the entire system which results in a commanded descent.

The air may be vented out from the compartment 354 to release ballastair, causing the pressure within the compartment 354 to drop and causingthe barrier 350 to move downward as oriented. The overall volume of theSPB 302 will remain the same, but the volumes of the compartments 352,354 may change as the barrier moves. The air may be vented out of thecompartment 354, as described herein.

The barrier 350 may be incorporated with multi-chamber SPB's havingthree or more chambers. For example, the compartment 352 or 254 may beexpanded by adding an additional chamber on the top or bottom asdesired. In some embodiments, the two-chamber SPB 302 may be duplicatedsuch that there are four chambers, For example, a first SPB 302 may bestacked on top of a second SPB 302, where the first and second SPB's 302would be fluidly separated from each other but have the internal barrierwithin each, as described. A hose or tube could extend to the upper SPB302. Thus, the configurations shown are merely some examples of thepossibilities with these features, and many others not explicitlydescribed herein are within the scope of this disclosure.

FIG. 15C depicts a cross-section of an embodiment of a three-chamber SPB303. The three-chamber SPB 300 of FIG. 14B may be modified into thesuper pressure blimp three-chamber SPB 303. As shown in FIG. 15C, thebarrier 350 may extend within the three chambers 300A, 300B, 300C todefine an inner compartment 352 and an outer compartment 354. The innercompartment 352 may include compressed lift gas. The inner compartment352 may be a closed compartment, for example a continuous and sealed offbag formed by the barrier 350. Thus, the barrier 350 in this embodimentmay be a closed volume. There may be a valve to allow for receiving liftgas inside the compartment 352 and then sealing the internal volume. Thecompartment 352 may reside within the outer compartment 354. The outercompartment 354 may include compressed air as described above, forexample from compressor 356.

The barrier or barriers 350 may form a closed envelope 351. The envelope351 may be located inside the outer continuous envelope that is formedby the gores 325A. The envelope 351 may define and separate the innercompartment 352 from the outer compartment 354. The envelope 351 mayextend between one or more chambers, e.g. the envelope 351 may occupyspace within the chamber 300A, 300B and/or 300C. The envelope 351 mayextend continuously between chambers. In some embodiments, the envelope351 may be formed of discrete and/or separate compartments, for examplewith fluidly separated compartments located within a respective chamber.The envelope 351 may have the same or similar features and/orfunctionalities as the barrier or barriers 350 described herein, andvice versa.

There may be one or more gas connections 311B between adjacent chambers300A, 300B and chambers 300B, 300C. The connection 311B may be coaxial.The connection 311B may allow for fluid to travel between adjacentchambers within the outer compartment 354 and outside of the barrier350. The connections 311B may protrude radially inwardly at or near thewaists to provide a structural attachment for the barrier 350 and/or toprovide for fluid passage between the chambers within the compartment354. In some embodiments, the connections 311B may not be included. Insome embodiments, lift gas bag restraints may be used to reduce orprevent “corking-up.” The restraints may for example prevent the barrier350 containing the compressed lift gas from corking-up the air passagebetween adjacent chambers and within the compartment 354 by form-fittingon the upper surface of each chamber 300B, 300C. In some embodiments, atwo-chamber SPB may use this type of internal “peanut” or closed volumeformed by the barrier 350.

The SPB 302 or 303, whether two-, three- or more-chambered, may havesome or all of the following features: a continuous multi-chamber superpressure balloon of “n” chambers; chamber with an internal bladder thatis fluidly connected to all “n” chambers; chambers that are fluidlyconnected to one or more compressors; where multiple discrete iterationsare connected in series (multiple multi-chamber SPB's chained together);a zero-pressure lift balloon is uppermost in the stack; and chambersoriented vertically, horizontally, or combination of horizontal andvertical.

In some embodiments, there may be lift gas within all of the chambers,such as SPB 303. The SPB 302 or 303, whether two-, three- ormore-chambered, may have some or all of the following features: a ZeroPressure Balloon (ZPB) fluidly connected to “n” vertically or axiallyoriented SPB's; one or more compressors and/or valves act to compresslift gas from the ZPB and store in the SPB chambers effecting a changein density of the system and thus a change in altitude; the arrangementof SPB chambers may have a compressor between the ZPB and the SPB and/orbetween each SPB chamber; one or more SPB's may also be attached fluidlyto a separate compressor to provide additional changes in vehicledensity.

In some embodiments, various ballonet systems may include the same orsimilar features and/or functionalities as described with respect toFIG. 15C. This embodiment may be described as a “peanut within apeanut.” Another example embodiment includes the continuousmulti-chambered (CMC) Super Pressure Blimp described in FIGS. 15A and15B.

The continuous multi-chambered super pressure design may allow for highvolumes and thus a greater mass of compressed air to serve as ballast.By placing another continuous multi-chambered super pressure balloonaround the first while maintaining the fluid connection of lift gasbetween chambers, the advantages of the systems described herein may beachieved with a reduced flight train. This may be of advantage, forexample, where rapid deployment is required or launch area isconstrained such as from a ship at sea.

The embodiments with the barrier 350 may provide several advantages,including but not limited to: eliminates the end fittings betweenfluidly separated SPB tanks and instead uses the circular outer fitting350B which saves mass; the manufacturing is easier as the continuousmulti-chamber pumpkin is made as one assembly, not multiple independentballoons that then have to be connected with interface fittings; agreater volume to mass ratio as compared to connecting independentpumpkins, for example in some versions maximizing at a 46% neck but formanufacturing ease and little loss of efficiency can neck down to 18% insome versions; and allows larger volumes for the air ballast tank (whichgives better altitude performance) while avoiding the global shapeinstability known as s-clefting.

FIGS. 15D and 15E are schematics showing an embodiment of amulti-chamber SPB 304 having two SPB chambers 300A, 300B which are shownas pumpkin SPB's, and used as a ballonet. In some embodiments, a stackedballonet system may be incorporated. Two ballonet systems may be fluidlyinterconnected, as shown in FIGS. 15D and 15E. The lower chamber 300Bhas the flexible barrier 350 installed which fluidly separates a portionof the volume of chamber 300B from chamber 300A. The barrier 350 may beconnected within the chamber 300B, for example along an inner surface ofthe skin or gores that form the chamber 300B. The barrier 350 may beconnected at or near the middle portion of the chamber 300B as shown. Insome embodiments, the barrier 350 may be connected at other locationswithin the chamber 300B.

The chambers 300A, 300B are fluidly connected by the fitting 305Abetween the two (e.g., the barrier 350 creates a ballonet in SPB 2). Thefitting 305A may be the same or similar as described, for example, withrespect to FIGS. 9C-9E, and may allow for fluid to travel between thechambers 300A, 300B within the compartment 352. The compartment 352 mayinclude lift gas and may extend from within the chamber 300A, throughthe fitting 305A, to a portion of the chamber 300B located above thebarrier 350.

There is gas in each chamber 300A, 300B. The chamber 300A holds alighter than air (LTA) lift gas (e.g., helium and/or hydrogen), andchamber 300B below the demarking flexible barrier 350 contains air,which may be drawn in and pressurized by a compressor. Air is more densethan LTA lift gas, and by varying the amount of air below the barrier350, the overall density of the entire balloon system can be varied,thereby providing the ability to vary the buoyancy of the balloon systemand to provide altitude control.

FIG. 15E depicts the barrier 350 in a configuration with more pressurewithin the compartment 354 relative to the configuration of FIG. 15D.FIG. 15D shows the system in a state where lift gas has expanded tooccupy substantially all or most available volume in the chambers 300A,300B through the fitting 305A. The compartment 354 has not beenpressurized. This configuration may represent the configuration requiredto ascend through the atmosphere and reach a point of equilibriumwhereby ascent would cease and the system would attain a float altitude,for example above 70,000 ft.

In order to descend the vehicle, atmospheric gases pressurize thecompartment 354 within the chamber 300B. The compartment 354 may bepressurized with a compressor, for example attached to the chamber 300Band fluidly connected to the compartment 354. The integrity of thechamber 300B may enable the density of atmospheric gases (air) withinthe compartment 354 to increase and thus change the buoyancy of theentire system effecting a descent of the entire system.

The flexible barrier 350 within the chamber 300B demarking the boundarybetween air and lift gas would expand, as shown in FIG. 15E. This mayconform or nearly conform to the inner shape of the chamber 300B andfurther compress the lift gas in the fluidly connected chamber 300A.This may reduce the effectiveness of the lift gas and assist theincrease in density and thus descent of the entire vehicle.

The various multi-chamber SPB's described herein may include one or moreof the following features: a lift balloon (LB) anchored by a SuperPressure Ballonet Balloon (SPBB) such as those described with respect toFIGS. 15A-15E; a L/B anchored by one or more SPBB's; a compressor isfluidly connected to one or more of the SPB chambers; the L/B is a SPB,for example having compartmentalized lift gas therein; the L/B is a zeropressure balloon (ZPB) such as the ZPB 200; one or more lift balloons(ZP or SP) are anchored by one or more SP ballast balloons such as theSPB 300, 301 and/or one or more SPBB's such as the SPB 302, 303, 304 or306; one or more of the balloons are connected to a flight train such asthe stratocraft 400; and/or one or more balloons are fluidly connectedto the compressor assembly 800 or compressor 810.

FIG. 16A is a side view of an embodiment of a two-chambered SPB 306. Asshown in FIG. 16A, in some embodiments, a two-chamber arrangement may beincorporated in parallel. The two chambers 300A, 300B may be served byone compressor 356. This may include a rigid structure to separate thetwo chambers 300A, 300B. Two supports 360 may extend from the compressor356 or a support structure thereof, with each support 360 respectivelyextending to the chamber 300A and 300B. Two fill tubes 362 may extendalong each support 360 from the compressor 356 to each of the chambers300A, 300B. In some embodiments, additional chambers may be added. Forexample, three or more chambers may be connected to the singlecompressor 356 with the support ladder 360 and compressor fill tube 362extending to each chamber. There may be three, four, five, six, seven,eight, nine, ten or more chambers and corresponding number of supports360 and fill tubes 362. As the number of chambers increases, one or moreadditional compressors 356 may be used. For example, there may be onecompressor 356 for every two or three chambers.

The SPB 306 may include one or more of the barriers 350. As shown thechambers 300A, 300B may each include the barrier 350. The barrier 350may be used within each chamber as described herein. Thus, in eachchamber 300A, 300B, the compressed air may fill a lower compartmentbelow the barrier 350 while lifting gas occupies the upper compartmentabove the barrier 350, etc. In some embodiments, the chambers 300A, 300Bmay not include the barrier 350 and may only provide a variable ballastfunction. In such embodiments, a lifting balloon such as the ZPB 200 maybe included above the chambers 300A, 300B.

FIG. 16B is an embodiment of an SPB 303A. The SPB 303A may include threechambers 300A, 300B, 300C. The chamber 300A may be serviced by acompressor 356A. Further, adjacent chambers may be separated by acompressor. For example, the chambers 300A and 300B may be separated bya compressor 356B. The compressor 356B may service one or both of thechambers 300A and 300B. Similarly, the chambers 300B and 300B may beseparated by a compressor 356B. The compressor 356B may service one orboth of the chambers 300B and 300B. The SPB chambers 300A, 300B 300C mayhave the same or similar features and/or functionalities as the otherchambers described herein. In some embodiments, there may be anarrangement of independent Super Pressure Ballonet Balloons (SPBB)Systems. There may be multiple SPBB's stacked vertically or arrangedhorizontally or combinations thereof. The SPBB may be arranged aboveand/or below a compressor. A ZPB may be used as a lift balloon.

Any of the various multi-chamber SPB's described herein may include oneor more of the following features: multi-stage compressor(s);compressors with differing performance characteristics/stages, forexample a compressor optimized for “low altitude”, a compressoroptimized for “medium altitude”, and a compressor optimized for highaltitude; fluidly connected SPB chambers.

In some embodiments, a first compressor (compressor 1) may pressurizeall fluidly connected SPB chambers 300A, 300B, 300C, a second compressor(Compressor 2) may then take the accumulated air from the first SPBchamber and pressurize the SPB chambers above it (e.g. the second andthird SPB chamber 300B, 300C) and a third compressor may take thefurther pressurized air from the second SPB chamber 300B and furtherpressurize the third SPB chamber 300C. This may increase the range ofaltitude control and allow for efficient descent from very highaltitudes. The differential pressure achieved may be high enough toeffect a change in buoyancy of the overall system.

FIG. 17A is a wire frame view of the two-chambered SPB 300 having awaist fitting 305B. FIG. 17B is a detail view of the waist fitting 305B.The waist fitting 305B may have the same or similar features and/orfunctionalities as other waist fittings described herein, such as thewaist fitting 305A, and vice versa. The waist fitting 305B may define orform an opening 306 therethrough. The opening 306 may extend through themiddle of the waist fitting 305B, which may be a structural ring asfurther described herein. The opening 306 may allow fluid such as gas totraverse the boundary between the chambers 300A, 300B and flow betweenthe chambers. The waist fitting 305B may be used with any of themulti-chamber SPB's described herein. Further detail of the waistfitting 305B is provided herein, for example in the section titled“BALLOON FITTINGS.”

O. Balloon Fittings

Various fittings may be used with the various LTA systems describedherein. Any of the fittings described in this section may be used withany of the systems, devices or methods shown in and/or described withrespect to FIGS. 1-17B, and vice versa. For example, various embodimentsof the fittings may be used with the LTA systems 100, 101, 102, 103 or104, and vice versa. As further example, any of the “waist” fittings orend fittings described in this section may be used with themulti-chamber SPB's described herein, for example the multi-chamberSPB's 300, 301, 302, 303, 304, 305, 306, 307A.

FIGS. 18A-18G depict various views of an embodiment of the waist fitting305B. The waist fitting 305B may be a solid junction fitting thatconstrains the narrowed tailored gores of multi-chamber SPB's to an“hour glass” configuration. An advantage of the waist fitting 305Binclude but are not limited to alignment of the fitting 305B using superpressure pumpkin balloon tendons. A similar attachment approach may beused at the end fittings to connect the tendons to the end fittings. Theuse of a similar technique as that used at fixing apex and nadirfittings on super pressure pumpkin balloons reduces complexity ofconstruction for the multi-chamber SPB.

The multi-chamber SPB may be a continuous multi-chamber SPB with thefixed waist constructed using single long hour glass seams. This mayreduce system mass by way of negating intermediate fittings from thesystem. Furthermore the continuous multi-chamber SPB with waist fittingmay take advantage of existing manufacturing techniques used for singlechamber SPB's, thus not requiring new and expensive manufacturing toolsand techniques. The fitting 305B may provide an optimized hoop radius ofthe super pressure pumpkin balloon. With multiple fluidly connectedchambers, the system is capable of storing considerable compressedatmospheric gas as ballast providing an extended vertical range ofperformance capability over systems with a single chamber SPB, includingover a single chamber ballonet SPB.

FIG. 18A is a perspective view of an embodiment of the waist fitting305B. The waist fitting 305B includes a body 307. The body 307 extendscircumferentially about a central axis. The body 307 may define theopening 306 on a radially inner side of the body 307. The opening 306may be empty as shown, or there may be one or more features locatedtherein. The continuous envelope of the SPB may extend through theopening 306. In some embodiments, the SPB, such as the gores 325A,extend through the opening 306. The SPB, such as the gores 325A, may ormay not attach to the fitting 305B. In some embodiments, portions of theSPB may extend through the opening 306 and portions of the SPB, forexample local brackets, straps or other features, may attach to thefitting 305B. The fitting 305B may be supported by tendons, as describedherein. The body 307 may be circular or approximately circular. In someembodiments, the body 307 may have other shapes, such as circular,non-circular, elliptical, oval, rounded, segmented, other suitableshapes, or combinations thereof. The body 307 may be formed from rigidor semi-rigid materials, including but not limited to metals, alloys,plastic, polymers, composites, fibers, other suitable materials, orcombinations thereof. The body 307 may be configured to extend arcuatelyaround the waist of a multi-chamber SPB, such as the waist 311A of theSPB 300 shown in FIG. 14D. The body 307 may be a single continuous partextending circumferentially about the axis. The body 307 may besurrounding an uninflated or underinflated SPB 300 which is extendedpartially through the body 307 and is then inflated. In someembodiments, the body 307 may be multiple parts connected together. Forexample, the SPB 300 may be inflated and then a multi-part body 307 maybe assembled together about the inflated waist 311A.

The fitting 305B may include an upper portion 308 and a lower portion309. The portions 308, 309 may form part of the body 307. The portions308, 309 may extend circumferentially along upper and lower sections ofthe fitting 305B about the central axis. The portions 308, 309 may beflat or generally sections.

An inner frame 322A may extend along a radially inner side of the body307. The inner frame 322A may extend along inner edges of the upper andlower portions 308, 309 and be attached thereto. The inner frame 322Amay provide a surface against which the waist 311A of the SPB maycontact and press against. The inner frame 322A may be a solid surfaceas shown, or there may be openings, other shapes, etc.

An outer frame 322B may extend along outer edges of the upper and lowerportions 308, 309 and be attached thereto. The outer frame 322B mayinclude a series of tabs 323 connected and forming tendon openings 324.One or more tendons 324 may extend through the openings 324. Theopenings 324 may facilitate alignment and positioning of tendons, asfurther described. The outer frame 322B may be a single piece ormultiple pieces attached together. The tabs 323 may be orientedvertically or generally vertically with horizontal sections therebetweento define upper and lower openings 324. The tabs 323 and/or openings 324may extend circumferentially around part, most, or all of the fitting305B.

FIG. 18B depicts the waist fitting 305B with the top portion 308 removedfor clarity. The bottom portion 307 is shown having an outer row 316 andan inner row 318 of attachments 319. The rows 316, 318 may extendcircumferentially along the body 307 with the attachments 319 protrudinglongitudinally between the upper and lower portions 308, 309. Theattachments 319 may be fasteners secured for example threaded to theupper and/or lower portions 307, 309. One or more of the attachments 319may include a bushing 321 surrounding the attachment 319. The bushing321 may rotate about the attachment 319 to provide a rotatable interfaceabout the attachment 319 to reduce friction and wear on the tendons andattachments 319, as further described. The attachments 319 in each row316, 318 may be staggered as shown. Each attachment 319 may have a clearpath extending radially outward from the attachment 319 to allow for acorresponding tendon to extend radially outward from the attachment 319.

FIG. 18C is a cross-section view of the waist fitting 305B. As shown,the attachment 319 may extend from the upper portion 308 to the lowerportion 309. The attachment may secure the portions 308, 309 together.Corresponding openings in the portions 308, 309 may receive theattachment 319 therethrough. The openings may be internally threaded tothreadingly engage an externally threaded attachment 319. The bushing321 may extend between opposing surfaces of the upper and lower portions308, 309 such that it may rotate between the portions 308, 309.

FIGS. 18D-18G depict portions of the fitting 305B with tendons extendingtherefrom in various configurations. FIG. 18D is a cross-section view ofthe waist fitting 305B shown with radially extending tendons 330. FIG.18E is a cross-section view of the waist fitting 305B, with a portionremoved for clarity, shown with radially extending tendons 330. FIG. 18Fis a cross-section view of the waist fitting 305B shown with axiallyextending tendons 330. FIG. 18G is a cross-section view of the waistfitting 305B, with a portion removed for clarity, shown with axiallyextending tendons 330.

The tendons 300 may have the same or similar features and/orfunctionalities as the other tendons described herein, such as thetendons 300 described with respect to FIGS. 3A-3B and the tendons 330A,300B, 330C, and vice versa. The tendons 30 may include the upper tendons330A and the lower tendons 330B. The upper tendons 330A may attach tothe inner row 318 of attachments 319. In some embodiments, the uppertendons 330A may attach to the inner row 318 and/or outer row 316 ofattachments 319. The upper tendons 330A may extend from the fitting 305Band along an outside of an SPB chamber located above the fitting 305B,such as the SPB chamber 300A shown in FIG. 14A. The upper tendons 330Aare shown extending radially outward in FIGS. 18D and 18E and axiallyupward in FIGS. 18F and 18G. This is for illustrative purposes only toshow that the tendons 330A may extend along a range of paths. Whenassembled with the SPB 300, the tendons 300A may extend upward at anangle to the horizontal and along the rounded outer surface the SPBchamber 300A.

The lower tendons 330B may attach to the outer row 316 of attachments319. In some embodiments, the lower tendons 330B may attach to the outerrow 316 and/or inner row 318 of attachments 319. The lower tendons 330Bmay extend from the fitting 305B and along an outside of an SPB chamberlocated below the fitting 305B, such as the SPB chamber 300B shown inFIG. 14A. The lower tendons 330B are shown extending radially outward inFIGS. 18D and 18E and axially downward in FIGS. 18F and 18G. This is forillustrative purposes only to show that the tendons 330B may extendalong a range of paths. When assembled with the SPB 300, the tendons300B may extend downward at an angle to the horizontal and along therounded outer surface of the SPB chamber 300B.

The tendons 300 may be attached to a respective one of the attachments319. The tendons 330 may have loops incorporated or formed into the endsof the tendons 330. The attachments 319 may be received through theopenings defined by the loops. The tendons 330 may be have a variety ofshapes at the end, such as circular, rounded, non-circular, segmented,other shapes, or combinations thereof. In some embodiments, the tendons330 may include end fittings that are attached to the attachments 319.The tendons 330 may be secured about the bushing 321. The bushing 321may rotate about the attachment 319. This may reduce wear on the tendon330. For example if the tendon 330 is biased laterally, instead ofrubbing on the attachment 319, the bushing 321 may rotate with therotating end of the tendon 330. This may preserve the integrity of theattachment 319 and the tendon 330.

The tendons 330 may extend from the fitting 305B to respective endfittings of the SPB. The upper tendons 330A may extend to the apexfitting 314A and the lower tendons 330B may extend to the nadir fitting314B, as shown in FIG. 14A. In some embodiments, the upper and/or lowertendons 330A, 300B may extend from the fitting 305B to another waistfitting 305B, such as shown in an described with respect to thethree-chamber SPB 300 of FIG. 14B. The tendons 330 may terminate at therespective end or waist fitting. Further details of various end fittingsthat may be used are described herein, for example with respect to FIGS.19A-19E.

The various multi-chamber SPB's described herein may include fittingsand/or annulus pieces at the apex and/or nadir ends of the upper mostand lowermost chambers of the SPB, such as the top 312A and/or bottom317A of the multi-chambered SPB 300 of FIG. 14D. These fittings may holdthe longitudinal tendons 330 in place, structurally accommodate thecombined force of the tendons 330, create a gas-tight seal where all theballoon gores 325 collect at the upper and lower portions 310, 315 ofthe SPB 300, ensure that no longitudinal loads are carried by theballoon skin 320, evenly distribute meridional loads between each gore325, carry the payload 730 and other flight loads, and evenly transmitpayload 730 and flight loads into the balloon material. Although variousembodiments of these fittings may be described with respect to a singlechamber SPB, it is understood that the fittings can be used at the apexand/or nadir ends of the upper most and lowermost chambers of acontinuous multi-chamber SPB.

FIG. 19A is a perspective view of an embodiment of an SPB 301 havingannulus end pieces 1605 at the apex and nadir of the SPB 301. FIG. 19Bis a perspective view of an embodiment of an end interface 1700 that maybe used at the nadir and/or apex of the various SPB's described herein.FIG. 19C is a perspective view of the SPB 301 having the interface 1700at the apex and nadir of the SPB 301. FIG. 19D shows an embodiment of afitting assembly 1801 at an apex of the SPB. FIG. 19E shows anembodiment of a fitting assembly 1801 at a nadir of the SPB. Thefeatures described with respect to FIGS. 19A-19E may be incorporatedwith any of the multi-chamber SPB's described herein.

Referring to FIG. 19A, the SPB 301 may have the same or similar featuresand/or functionalities as the SPB 300, and vice versa, except asotherwise described. The SPB 301 may be an uppermost or lowermostchamber of a multi-chamber SPB. The SPB 301 may have skin 1620 made ofgores 1625, which may be heat sealed, gore shaped film pieces, and theresultant circular top opening 1612 and bottom opening 1617 of theassembled SPB 301 may each include regions 1610 of alternatingnon-uniform layers of sealed seam allowance stack-ups along with thegores 1625. The SPB 301 may include one or more tendons 1630 extendinglongitudinally as shown. The skin 1620, gores 1625 and tendons 1630 ofthe SPB 301 may have the same or similar features and/or functionalitiesas, respectively, the skin 320, gores 325 and tendons 330 of the SPB300, and vice versa.

To alleviate the problem of trying to make a gas tight seal against theuneven layering of the gores 325 and their attachment seam construction,a single, flat annulus shaped film piece or annulus pattern piece 1605may be heat sealed at its outer diameter to this non-uniform balloonopening 1612 where the gores 1625 converge, and then clamped at aninterface 1700 (see FIG. 19B) at its inner diameter. The interfaces 1700may include various fitting assemblies, for example as shown in FIGS.19C-19E. The annulus pattern piece 1605 may create a flat, uniformsurface for clamping, thus ensuring a more gas tight seal between theballoon film and the apex/nadir interfaces 1700. The annulus patternpiece 1605 may be configured to address stress risers in the transitionfrom the bulge shape of the inflated gores 1625 to the flat shape of theannulus pattern piece 1605. In some embodiments, the gores 1625 may beattached to a single or double layer annulus (e.g., an “0” shape) ofmaterial that forms the structural connection of the gore 1625 film andcan be clamped into an airtight seal in the interfaces 1700 at the apexand nadir sides of the SPB 301, as shown in FIG. 19A. Note that fittinghardware components and tendons are not shown for clarity.

As shown in FIG. 19B, the interface 1700 may include a single layerannulus pattern piece 1605 seamed (e.g. heat sealed) to the gores 1625(a single gore 1625 is shown for clarity) or a two-layer annulus 1605encapsulating the balloon gores 1625. The interface 1700 may be includedat the top 1612 and/or bottom 1617 of the SPB 301. The annulus patternpiece 1605 may comprise the same material (but not necessarily the samethickness) as the gores 1625. In both cases seals 1705, such as siliconegaskets, etc., can be used to seal the clamp interface, as shown in FIG.19B. A clamping ring 1710 may be secured to a plate 1715 with theannulus pattern piece 1605 and gores 1625 clamped in between theclamping ring 1710 and the plate 1715. A fastener 1717, such as a bolt,screw, etc., as shown may secure the clamping ring 1710 and the plate1715 together. In some embodiments, in addition or alternatively tofasteners 1717, other suitable connections may be implemented, such asclamps, clips, adhesives, other suitable mechanical connections, orcombinations thereof. The plate 1715, shown partially in cross-section,may be a structural member having a flat or generally flat shape and acircumferential, e.g. circular or otherwise rounded, perimeter. Theplate 1715 and clamping ring 1710 may be made of metals, alloys,composites, polymers, plastics, other suitable materials, orcombinations thereof. The SPB 301 may include on or more tendontermination posts 1720. The posts 1720 may be connected to the plate1715 as shown. Each of the tendons 1630 may couple with, for exampleattach directly to, one or more of the tendon termination posts 1720.

FIG. 19C shows an embodiment of the pressurized SPB 301 having an upperfitting assembly 1801 and a lower fitting assembly 1802. FIGS. 19D-19Eare close up views of, respectively, the fitting assemblies 1801 and1802. The fitting assemblies 1801, 1802 may include the interface 1700as described above. The fitting assemblies 1801, 1802 may be different.In some embodiments, the fitting assemblies 1801, 1802 may be the same.As shown, the outer diameter of the annulus pattern piece 1605 may beattached to the balloon gores 1625 with a sealer, for example a 12″portable impulse heat sealer. The seals may be carefully positioned sothat pockets of ambient air are not trapped in crossing heat sealpattern as seen in the figures. This may prevent leakage at theattachment heat seal on either end of the SPB 301. The skin 1620 maytransition from the gores 1625 to the annulus pattern piece 1605 at agore/annulus transition 1805. The transition 1805 may be a region of thegores 1625 and annulus pattern piece 1605 where the gores 1625 and piece1605 overlap, are adjacent to each other, etc.

The clamping ring 1710 may secure the annulus pattern piece 1605, asdescribed, for example to the plate 1715. As shown, the fitting assembly1802 may include an outer ring 1712. The outer ring 1712 may beconnected to the plate 1715 and/or clamping ring 1710, for example byone or more connecting members 1714 (only some of which are labeled inthe figures for clarity). The connecting members 1714 may be fasteners,such as bolts, etc., standoffs, or other structural connections. In someembodiments, one or more of the connecting members 1714 may be used astendon termination posts 1720, or vice versa. The rings 1710, 1712 maybe axially offset, for example by the connection members 1714. One ormore cables 1718, such as hoists or other supporting members, may beconnected to the SPB 301 by extending the cables 1718 through theopening between the offset rings 1710, 1712. The cables 1718 may be usedto secure the SPB 301 to the ZPB 200, or to ground equipment such as acrane for manufacturing, assembly, testing, etc. The fitting assembly1802 may include a fitting 1716, such as a plate with openings,protrusions, etc., which may be used for connecting the SPB 301 toanother structure, such as to or with the payload support 700, thepayload 730, the parafoil 680 or other descent vehicle, the ladderassembly 610, other structures, or combinations thereof. The ring 1712,connecting members 1714, plate 1715, and/or fitting 1716 may be formedfrom metals, alloys, composites, polymers, plastics, other suitablematerials, or combinations thereof.

FIGS. 20A-20C depict schematics of systems and methods for constructinga rope ring fitting 305C. The fitting 305C may be used in someembodiments on the multi-chamber SPB's described herein. The fitting305C may be used alternatively or in addition the fitting 305B. FIG. 20Adepicts a stanchion system for forming the rope ring. FIGS. 20B and 20Cdepict detail views of a portion of the system of FIG. 20A where theportions 371, 372 are wrapped together. The rope ring construction canbe done such that the strains from flight pressurization tension, slackstrain, and/or temperature effects are accounted for during the roomtemperature low stress construction. The belt diameter of a multi-turnconstruction ring 305C (instead of one big rope, numerous wraps of asmaller rope so that there is only one small splice) can be accurate soas not to over stress the balloon material at the necking-in location.This is an example method to construct the rope ring 305C such that theslack strain is reduced or minimized and the splice can be constructedunder tension to produce as accurate a length as possible with thismaterial.

The portion 371 may have an end 371A and the portion 372 may have end372A. The rope is wrapped around a first stanchion 374 and a secondstanchion 376. The portions 371, 372 are then brought together. Theportion 371 is wrapped around the portion 372 at the section 374. Theportion 372 is wrapped around the portion 371 at the section 375. Thewraps may be under nominal tension to reduce the slack strain. A splicelink at the ends 371A, 372A may be bowed out slightly from the wraps.The splice may be made with an isolation tension. The ends 371A, 372Amay be pulled to tighten the splice. The splice may be sewn while inthis double-tensioned configuration.

P. Embodiments with Variable “Free Lift” Gas

The LTA systems described herein may include balloon envelopes, orportions thereof, that each provide for lift, for descent, or for liftand descent. For example, the zero pressure balloons (ZPB) describedherein may provide solely or primarily lifting functions for the LTAsystem. For example, the super pressure balloons (SPB) may providesolely or primarily for descending functions for the LTA system. Asdescribed herein, such lifting or descending functions may be providedusing balloons with multiple chambers or envelopes, whether fluidlyconnected or separated. See, for example, the section “N. CONTINUOUSMULTI-CHAMBER SUPER PRESSURE BALLOON.”

In some embodiments, these and other LTA systems described herein may bemodified as needed for particular missions or for better performancecharacteristics for a selected mission. Some missions and the attendantrequirements may benefit from and allow for use of existing envelopes toprovide for multiple functions. In some embodiments, the balloonenvelopes, or portions thereof, may provide for lift (ascent) anddescent. Some embodiments provide for the use of “free lift” gas, asfurther described herein. For example, an interior volume of an SPB,whether single or multiple chamber, may be used to hold lifting gas toprovide or supplement “free lift” to the system for an initial part offlight, and then the lifting gas may be expelled and the same interiorvolume of the SPB that held the lifting gas may then be used for holdingvariable amounts of ballast air. The SPB may include a valve thatselectively opens to vent or otherwise release the lifting gas and thencloses after release. The valve may be located at or near the top orupper portion of the SPB since the lifting gas will rise within the SPBto the upper portion. Some, most or all of the lifting gas may bereleased. Then, the SPB may be filled with ambient air and the ambientair may later be released, to provide variable downward forces to thesystem. Further, in some embodiments, a fill tube may extend from theSPB to a payload support and allow for filling the SPB with lifting gasprior to launch. For instance, a compressor may connect to the SPB viathe fill tube, and an inlet such as a manifold may allow for providingthe lifting gas to the SPB via the fill tube. A one-way valve, such as acheck valve, may prevent backflow of gases or air through the inlet ormanifold. These and other features are described herein in detail.

The features for free lift described herein may be incorporated into anyof the LTA systems and methods described herein, such as those shown inand described with respect to FIGS. 1-20C. In particular, the SPB 300,and any variations thereof, may incorporate features to provide for freelift. In some embodiments, the LTA systems 106A, 106B, 106C mayincorporate features to provide for free lift. In some embodiments, theSPB 300A, 300B, 300C, 302, 303, 304, 305′, 306 and 307A may incorporatefeatures to provide for free lift.

The use of “free lift” gas can be advantageous for multiple reasons. Forinstance, free lift may assist with addressing conditions imposed bywind or other atmospheric conditions. As one example, for LTA systemswind at ground level may be different in magnitude and/or direction fromhigher levels. The differences between ground level and levels up to andjust exceeding the top or crown of the upper balloon envelope (e.g.above the ZPB 200) can have large effects on the stability of the LTAsystem 100. These effects may occur to an LTA system 100 that is in theprocess of standing up, that is already stood up, and/or in the momentsfollowing release. These altitude levels can range from ground level to100 or more, 200 or more, 3000 or more, 400 or more, or 500 or more feetabove the ground level, depending on the height of the LTA system 100.Stratifications or gradients in the wind movement with respect toincreased altitude can impose variable forces on the LTA system 100.Such forces may be counteracted with the use of free lift delivered withthe features described herein.

As another example, the ZPB 200 may have a very large surface area whichcan be subject to winds at the levels described. Furthermore, thecharacteristic of the “bubble” shape of the ZPB 200 may result ineffects similar to those of lifting surfaces such as airfoils andlifting bodies. The passing of wind over a rising, risen, tetheredand/or just released LTA system 100, such as over the ZPB 200, canresult in a low pressure area developing on a side of the balloonbubble, such as the downwind side. The difference in pressure on twosides of the LTA system 100 may result in a disturbing force, e.g. adownward force, that can cause the LTA system 100 to sway or moveundesirably, in some cases tip or fall over. The balloon system undersuch conditions may, upon release, fail to ascend swiftly and may dragthe payload and flight train across the launch area. Such movement couldrepresent a hazard to crew and observers and may jeopardize the mission.The effect of these disturbances may be prevented or mitigated usingfree lift, for example by using fee lift in order to effect swift ascentand obstacle clearance, as described herein.

In some embodiments, the LTA system 100, e.g. the ZPB 200, is providedwith more lift gas than is necessary for the mass of the LTA system 100in order to achieve a swift ascent. This is known as “free lift.” Thefree lift may be represented as a percentage of neutral buoyancy lift,or as a percentage of the amount of lift necessary to keep the LTAsystem 100 at a constant altitude. Excessive free lift after launch canresult in ascending above the target altitude. This may result in damageto the LTA system 100 envelope, including catastrophic envelope failure.In order to avoid these and other issues, free lift may be ventedthrough escape ducts built into the balloon envelope, e.g. in the lowerpart of the balloon envelope. In some embodiments, escape ducts may belocated in the lower part of the balloon envelope for the ZPB 200. Insome embodiments, alternatively or in addition to the ZPB, free lift isprovided with lifting gas stored within the SPB, or chambers or portionsthereof, as further described.

Some embodiments of the LTA system 100 may therefore provide for aspecified mass of lift gas. The overall mass of lift gas may be providedwithin the ZPB 200, the SPB 300 or both the ZPB 200 and SPB 300. Variousportions or ratios of the lift gas may be provided in both the ZPB 200and SPB 300. The SPB 300 may contain 10%, 20%, 30%, 40%, 50%, 60%, 70%,80% 90% or more of the free lift gas, with the ZPB 200 containing thecorresponding remainder of free lift gas. The required mass may bedetermined accurately using the approaches described herein. Accuratedetermination of the required mass of lift gas will ensure reaching atarget altitude without overshooting and while allow for quick clearanceupon launch, as described. In some embodiments, the altitude controlmaneuvers using free lift gas may be accomplished in the center of aperformance envelope for the LTA system 100 so that the altitudemaneuvering can begin on the first ascent within the maneuveringaltitudes.

In some embodiments of the LTA system 100, a portion of the free liftgas is stored in the SPB 300. After release and swift ascent of the LTAsystem 100 is achieved, including clearing ground obstacles, the LTAsystem 100 attains a zero relative velocity with respect to the wind andthe excess lift gas can be safely vented at the appropriate timeavoiding an overshoot of the target altitude.

The amount of free lift required for a zero-pressure balloon based LTAsystem may be a function of the lift gas chosen, the time of day whenlaunched, how fast the ascent needs to be, and the direction and speedof ground winds. Ground wind considerations may have the least influenceas compared to the other parameters. In some embodiments, normal freelift for a dawn launch for a large version of the LTA system 100 usinghelium lift gas is 10% or about 10%. In some embodiments, it may be fromabout 2% to about 20%, from about 4% to about 17%, from about 6% toabout 14%, or from about 8% to about 12%. If the launch of the LTAsystem 100 is at night, then the required free lift may increaserelative to a launch as dawn.

If hydrogen gas is used, then the free lift percentage required woulddecrease relative to the required percentage using helium gas. Heliumhas a very marked adiabatic expansion chilling effect on gas temperaturewhich reduces the effectiveness of the free lift (cold gas shrinks involume and so loses buoyancy). Hydrogen gas does not cool down to thesame extent upon expansion as helium does. Ascending balloons with 10%free lift helium may stall their ascent when the balloon reaches thetropopause. If the test range is small and the jet stream winds arefast, stalling out at the tropopause means the balloon is quickly beingblown out of the test range. So, such a balloon with a need to pass thejet stream altitudes quickly could either have had more launch freelift, and/or it could drop solid ballast to punch its way thru. Further,ground winds during launch, besides producing drag, could have “falselift” on the order of 4% or about 4% effective free lift. This is anaerodynamic effect over the balloon shape, but since just about all freelift situations require more, this is usually not a consideration.

The LTA system 100 may have in the range of 1% to 15% residualisothermal free lift left in the ZPB 200 to operate in the middle of itsperformance envelope. In some embodiments, the ZPB 200 may require 1% ormore, 5% or more, 10% or more, or from about 1% to about 20% residualisothermal free lift left to operate in the middle of its performanceenvelope. By placing the left-over gas from the desired total launchfree lift into the SPB 300, which may also be in the range of 1% to 15%,a higher amount of free lift is available when needed and is vented whenno longer of use somewhere along the trajectory. In some embodiments,the SPB 300 may have 1% or more, 5% or more, 10% or more, or from about1% to about 20% left-over gas from the desired total launch free lift.The various portions of the LTA system 100 may be precisely filled withthe lifting gas using an accurate flow rate meter.

FIG. 21 is a side view an embodiment of the LTA system 100. The system100 includes the ZPB 200, SPB 300, and stratocraft 400 as describedherein. The LTA system 100 may include the same or similar featuresand/or functionalities as described herein for other LTA systems, andvice versa. The stratocraft 400 may include various subsystems, such aspower, control, communications, air intake, air release, payloaddescent, multi-stage, payload support 700 which may include thecentrifugal air compressor assembly, the ladder assembly 610, optionallyalso comprising solar panels 630. The parafoil 680 may also be included.

The SPB 300 of FIG. 21 may include the same or similar features and/orfunctionalities as described herein for other SPB's, and vice versa. Insome embodiments, the SPB 300 may include one or more compartments orchambers, as described herein. For example, the SPB 300 of FIG. 21 mayinclude the same or similar features and/or functionalities as any ofthe SPB's 300 of FIGS. 1, 3A-3B, 4A-4B, 9A-9E, 13A-13C and 14A-14D, theSPB 305 of FIG. 13D, the SPB 302 of FIGS. 15A-15B, the SPB 303 of FIG.15C, the SPB 304 of FIGS. 15D-15E, the SPB 306 of FIG. 16A, the SPB 307Aof FIG. 16B, the SPB 301 of FIGS. 19A-C, and vice versa.

As shown in FIG. 21, the SPB 300 may include a ballast air valve 398and/or a lifting gas valve 399. The valve 399 may allow for ventinglifting gas from within the SPB 300 to the surrounding atmosphere. TheSPB 300 may be configured to receive a lifting gas, for example withinan interior volume therein. The lifting gas may be received into thesame interior volume as ambient air is received into after the liftinggas is released from the interior volume, as further described herein.The valve 398 may be used to release the lifting gas at different stagesof flight. In some embodiments, different valves may be used to vent thelifting gas and the ambient air. The ballast air may be vented out ofthe valve 870 of the compressor manifold 850 via the air hose 690, asdescribed herein. Alternatively or in addition, in some embodiments, theSPB 300 may include an additional valve or valves, such as the valve399, on the SPB balloon envelope for venting the ballast air directlyinto the atmosphere from the envelope.

Features for SPB's having two or more chambers, such as the SPB's 302,303 of FIGS. 15A-15C, may be incorporated into SPB's having one chamber,such as into the SPB 300 shown in FIG. 21. In some embodiments, amulti-chamber SPB may define one continuous interior volume whichreceives both the lifting gas and the ambient ballast air at differentstages of altitude control.

In some embodiments, the lifting gas may be received into a separatedcompartment or compartments within the SPB 300. The compartment may belocated at an upper portion of the SPB 300. The lifting gas compartmentmay be separated from a ballast air compartment, such as the compartment354 as described herein. The lifting gas compartment may be separated bya barrier, such as the barrier 350 described herein.

As further shown in FIG. 21, the valve 398 may allow for venting ballastgas, such as air, from within the SPB 300 to the surrounding atmosphere.This may be an alternative to, or additional means for, venting theballast air through the air hose 690 and out the valve 870 at thepayload support 700, as described herein. In embodiments that use thevalve 398, the valve 398 may be opened to allow for air to escape from aballast air compartment, as described above. As mentioned, the othervalve 399 may be used to release both the lifting gas and the ballastair at the different stages of flight. In some embodiments, the valve398 may be used to release both the lifting gas and the ballast air.

The valves 398, 399 may be located at various portions of the SPB 300.The lifting gas valve 399 may be located at or near an upper portion ofthe SPB 300. The valve 399 may be located at the apex or top of the SPB300. The valve 399 may be incorporated into a fitting at the apex of theSPB 300, such as the various fittings described herein. There may bemultiple lifting gas valves 399. In some embodiments, the one or morevalves 399 may be located to prevent or mitigate the effect of ventingthe gas on the position of the LTA system 100. For example, multiplevalves 399 may be located so that opposing forces are generated on theLTA system, due to the momentum of the venting gas, such that a net zeroforce or near zero force acts on the LTA system 100 as a result of theventing gases. The air ballast valve or valves 398 may be positioned toachieve a similar effect.

The valves 398, 399 may be controlled remotely via communication fromthe ground. The control system 1000 of FIG. 10 may be used to controlthe valves 398, 399. The valves 398, 399 may be remotely controlledvalves or other devices for selectively releasing air or other gasesfrom the balloons. The valves 398, 399 may be configurable between openand closed positions. The valves 398, 399 may be opened variable amountsto control the quantity and/or speed of gas or air that is allowed toescape from the balloon. The amount of opening of the valves 398, 399may be based on a variety of considerations, including but not limitedto the desired exit flow rate, the current pressure within the balloon,the ambient pressure, the temperatures inside and/or outside theballoons, the altitude of the LTA system 100, the location of the venton the balloon skin, and others.

Either or both of the valves 398, 399 may be controlled similarly to anyvalve described herein, such as the valve 1030 described herein withrespect to FIG. 10. The various sensors described herein, such as thesensors 1020 and/or others, may be used to detect that various relevantinformation, such as altitude, ambient air density or pressure, LTAsystem velocity, or other parameters, in order to control the valves398, 399. The valves 398, 399 may be controlled in order to achievedesired altitudes and/or latitudes and longitudes as described herein,for example with respect to FIGS. 11A-12B. The valve 399 may becontrolled to selectively allow for venting excess lifting gas, forexample after a desired altitude has been reached. The valves 398, 399may be controlled automatically based on sensor input and computercommands and communications, or the valves 398, 399 may be controlledmanually by ground operators, or by a combination of automatic andmanual controls.

In some embodiments, the system 100 may comprise the ZPB 100 configuredto receive therein a first mass of LTA gas to provide a first upwardlifting force to the balloon system 100 and the SPB 300 may comprise aninterior volume configured to receive therein a second mass of LTA gasto provide a second upward lifting force to the balloon system. The SPB300 may comprise the valve 399 configured to be opened and closed, wherethe valve 399 when opened allows for release of at least a portion ofthe second mass of LTA gas from the SPB 300 through the valve 399 to asurrounding atmosphere to decrease the second upward lifting force. Thevalve 399 when closed does not allow for release of the second mass ofLTA gas from the SPB 300 through the valve 399 to the surroundingatmosphere. The interior volume of the SPB 300 may be furtherconfigured, after release of the at least a portion of the second massof LTA gas from the SPB 300, to receive therein a variable amount ofambient air from the surrounding atmosphere to provide a variabledownward force to the balloon system 100. The lifting gases may behelium or hydrogen. The lifting gas in the ZPB and the SPB may be thesame type of gas or different types.

The lifting gas may be vented through the valve of the SPB 300 after theLTA system 100 clears ground obstacles and/or prior to performingaltitude control maneuvers. The lifting gas may be vented from the SPB300 prior to receiving ballast air therein. Some, most or all of thelifting gas may be vented from the SPB 300 prior to receiving ballastair therein. The valve may be opened to allow for venting 30% or more,40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% ormore, 95% or more, 96% or more, 96% or more, 98% or more, 99% or more,or 100% of the lifting gas from the SPB 300. The valve may be opened fora set time to ensure adequate evacuation of the lifting gas from the SPB300. The valve may then be closed and the compressor 810 started tocharge the SPB 300 with ambient air to provide ballast air through theair hose 690 and to a valve connected to the lower portion of the SPB300 such as at the base of the lower chamber 300B.

In some embodiments, the system 100 may include a compressor, such asthe compressor assembly 800 and/or the compressor 810. The compressormay be located with the stratocraft 400, such as with the payloadsupport 700. The system 100 may include a fill tube such as the air hose690. The fill tube may extend along the ladder assembly 610, asdescribed herein, for example with respect to FIGS. 5B-5C. The fill tubemay fluidly connect the compressor to the interior volume of the SPB300. The fill tube may be configured to receive the second mass of LTAgas and to allow the second mass of LTA gas to flow through the filltube to the interior volume of the SPB 300. The LTA gas may be loadedinto the SPB 300 while the system 100 is on the ground and prior to orduring launch. The LTA gas may be loaded via an inlet manifold on thestratocraft 400, such as the manifold 850 described herein, for examplewith respect to FIGS. 7A-7B. A flow meter and/or other instrument may beused to accurately measure the mass of LTA gas provided to the SPB 300.The LTA gas may pass through the manifold 850 past a one-way check valveinto the air hose 690 that extends from the payload support 700 to theSPB 300, for example from the compressor exhaust manifold 850, up theladder assembly 610 via the air hose 690, and into the SPB 300. The airhose 690 or other fill tube may connect to the base or lower portion ofthe SPB 300, which may be located on the lower-most chamber 300B or300C, etc. of the SPB or of the continuous multi-chamber (CMC) SPB asdescribed herein. Further, the compressor 810 may be configured toprovide the variable amount of ambient air from the surroundingatmosphere to the interior volume of the SPB 300 via the same fill tubesuch as the air hose 690, as described herein. In some embodiments, adifferent fill tube may be used to provide the lifting gas and ballastair. “Lifting gas” and “LTA gas” are used interchangeably herein.

In some embodiments, the system 100 may include an LTA gas inlet fluidlyconnected with the fill tube along an inlet flow path. The LTA gas inletmay be configured to receive the second mass of LTA gas and to allow thesecond mass of LTA gas to flow along the inlet flow path to the filltube. The one-way valve may be located within the inlet flow path andconfigured to prevent backflow of the LTA gas across the valve. Forexample, the air hose 690 may connect to the opening 854 of the manifold850, shown for instance in FIGS. 7A-7B. The inlet may be an opening onthe manifold 850 that fluidly connects with the air hose 690 and/or theopening 854 of the compressor. In some embodiments, the valve 870 of thecompressor assembly 800 may be used to release the ballast air from theSPB, and the valve 399 of the SPB 300 may be used to release the LTAgas, as described.

The LTA gas may be used for free lift during initial stages of flight,for example until an altitude maneuver is first performed. The system100 may be used according to various methods. In some embodiments, amethod of controlling the buoyancy of the system 100 is used. The methodmay comprise releasing, while the high altitude balloon system 100 is inflight, the LTA gas from the interior volume of the SPB 300 to asurrounding atmosphere, and receiving, while the high altitude balloonsystem is in flight, ambient air from the surrounding atmosphere intothe interior volume of the SPB 300. The LTA gas may be mostly orcompletely emptied from the interior volume of the SPB 300 prior toproviding the ballast ambient air. In some embodiments, the LTA gas andthe ambient air are not mixed within the interior volume.

The method may further comprise receiving, prior to the high altitudeballoon system 100 being in flight, the LTA gas into the interior volumeof the SPB 300. This may be done on the ground prior to or duringlaunch, as described. Prior to releasing the LTA gas from the interiorvolume of the SPB 300, the system 100 may lift or ascend to a firstaltitude. The first altitude may be the altitude at which obstacles arecleared, at which a first altitude maneuver is to performed, or otheraltitudes. After the LTA gas is expelled, the ambient ballast air may bepumped into the SPB 300, as described. At least a portion of thatambient air from the interior volume of the SPB 300 may be released tothe surrounding atmosphere, for example by adjusting the valve 870 to anopened configuration.

The expelling of the lifting gas from the SPB 300 may decrease theupward forces on the LTA system 100, which, depending on environmentalconditions and system 100 characteristics, may lead to a slower ascentrate, maintenance of neutral buoyancy, maintaining a constant altitude,or to descent of the system 100. The adding of ambient ballast air intothe SPB 300 may increase a downward force on the LTA system 100, which,depending on environmental conditions and system 100 characteristics,may lead to a slower ascent rate, maintenance of neutral buoyancy,maintaining a constant altitude, or to descent of the system 100. Theexpelling of ambient ballast air from the SPB 300 may decrease adownward force on the LTA system 100, which, depending on environmentalconditions and system 100 characteristics, may lead to a slower descentrate, maintenance of neutral buoyancy, maintaining a constant altitude,a faster ascent rate, or to ascent of the system 100. Environmentalconditions may include atmospheric density, temperature, pressure, timeof day or night, etc. System 100 characteristics may include altitude,size, shape, volume, mass, etc.

FIGS. 22A and 22B show two embodiments of an LTA system 110 and 111,respectively. The LTA systems 110, 111 are variable altitude air ballastballoon systems with alternative continuous multi-chamber tankarrangements. The LTA systems 110, 111 include the ZPB 200, the firstSPB chamber 300A, the second SPB chamber 300B, and the stratocraft 400.The stratocraft 400 includes the ladder assembly 610, the solar panelassembly 630 and the payload support 700. The LTA systems 110, 111 mayinclude the same or similar features and/or functionalities as the LTAsystem 100 of FIG. 21 or of any other LTA system described herein, andvice versa.

As shown in FIG. 22A, the LTA system 110 includes two chambers 300A,300B coupled together. The chambers 300A, 300B may be a continuousmulti-chamber (CMC) SPB as described herein. The chambers 300A, 300B mayform a continuous inner envelope as described herein, for example withrespect to FIGS. 14A-15D. There may be a waist 311A, as describedherein, formed between the chambers 300A, 300B. There may be a waistfitting 305B, as described herein, located at the waist 311A between thetwo chambers 300A, 300B. Other waist fittings such as the waist fitting305A, etc. me be incorporated.

In some embodiments, the chambers 300A, 300B may be separated by aninternal barrier, as described herein. The barrier may be between thechambers, within one or both of the chambers, or in otherconfigurations. The barrier may have the same or similar features and/orfunctionalities as the barrier 350 described herein.

As shown in FIG. 22B, the LTA system 110 includes two chambers 300A,300B coupled together but separated by the waist fitting 305B. Thechambers 300A, 300B may form separated chambers as described herein. Insome embodiments, the chambers 300A, 300B may be fluidly separated. Insome embodiments, the chambers 300A, 300B may be fluidly connected, forexample by a hose or other features as described herein. There may be awaist 311A, as described herein, formed between the chambers 300A, 300B.There may be a waist fitting 305A, as described herein, located at thewaist 311A between the two chambers 300A, 300B. Other waist fittingssuch as the waist fitting 305B, etc. may be incorporated.

In some embodiments, the chambers 300A, 300B may be separated by aninternal barrier, as described herein. The barrier may be between thechambers, within one or both of the chambers, or in otherconfigurations. The barrier may have the same or similar features and/orfunctionalities as the barrier 350 described herein.

As shown in FIGS. 22A and 22B, the SPB 300A may include a lifting gasvalve 399A. The lifting gas valve 399A may have the same or similarfeatures and/or functionalities as the valve 399. The valve 399A mayvent lifting gas stored in the SPB chamber 300A. In some embodiments,the valve 399A may vent lifting gas stored in the SPB chamber 300Aand/or the SPB chamber 300B.

The SPB 300B may include a lifting gas valve 399B. The lifting gas valve399B may have the same or similar features and/or functionalities as thevalves 399, 399A. The valve 399B may vent lifting gas stored in the SPBchamber 300B. The SPB 300B may not include the lifting gas valve 399B,such that there is only one or more valves 399A located at the top orupper portion of the SPB 300A.

In some embodiments, the valve 399B may vent lifting gas stored in theSPB chamber 300B and/or the SPB chamber 300A. In some embodiments, thelifting gas valve 399A vents lifting gas from a compartment within SPBchamber 300A and the lifting gas valve 399B vents lifting gas from acompartment within SPB chamber 300B. Each chamber 300A, 300B may havetwo or more of the respective valves 399A, 399B. Further, there may beone, three or more SPB chambers, with each chamber having one or more ofthe valves 399A, 399B.

In some embodiments, the LTA systems 110, 111 may include ballast airvalves, as described herein. For example, ballast air valves may beincorporated into the compressor assembly 800, such as the valve 870 asdescribed herein, for example with respect to FIGS. 7A-7B. In someembodiments, ballast air valves may be incorporated into the balloons300A and/or 300B, such as the valves 398 described with respect to FIG.21.

FIG. 23 shows an embodiment of a LTA system 112 having embodiments ofthe SPB chamber 300A and the SPB chamber 300B. One or both of the SPBchambers 300A, 300B may contain one or more of the valves as describedherein, such as one or more of the valves 399, 398. The LTA system 112may be a variable altitude air ballast balloon system, as describedherein. The LTA system 112 may include the ZPB 200 and the stratocraft400 having the ladder assembly 610, the solar panel assembly 630 and/orthe payload support 700. The LTA system 112 may include the same orsimilar features and/or functionalities as the LTA system 100 of FIG.21, as the LTA systems 110 or 111 of FIGS. 22A-22B, or of any other LTAsystem described herein, and vice versa.

The LTA system 112 is shown on the ground. The LTA system 112 has beensupplied with lifting gas to “stand” the system up. The ZPB 200 portionof the LTA system 100 may be precisely filled using an accurate flowrate meter. After the ZPB 200 portion is filled and then released, theLTA system 100 may then be “stood up,” as shown in FIG. 23 Additionalfree lift gas may then be added to the SPB 300, for example via a fillinlet valve that is part of the variable air ballast air intake manifold850. This may be through a valve of the manifold 850 in the stratocraft400 and/or through a valve or vent in the SPB 300, as described herein,for example with respect to FIGS. 21-22B. The LTA gas may be providedthrough an inlet of the manifold past a one-way valve into the air hose690 to the SPB 300, as described.

The LTA system 112 is thus shown in FIG. 23 in “stand-up” configurationprior to ascent from the ground. The SPB 300A and/or 300B may includesupplemental lifting gas for free lift, as described herein. Forexample, the SPB 300A and/or 300B may have the same or similar featuresand/or functionalities as the SPB's described with respect to FIGS.21-22B. The SPB 300A and/or 300B may therefore include the valves 399A,399B, etc. The LTA gas may be provided to the SPB 300 via a connectionat or near the bottom or base of the SPB 300, such as a nadir fitting asdescribed herein. The LTA gas may then rise through the lower chamber300B and to the upper chamber SPB 300 via the interior continuousenvelope defined by the chambers 300A and 300B, such as to the upperportion within the chamber 300A, to partially inflate the chamber 300Aas shown. In some embodiments, the LTA gas may be exclusively locatedwithin the chamber 300A. In some embodiments, the LTA gas may also belocated partially within the chamber 300B.

As shown in FIG. 23, the SPB chamber 300A may be under-expanded relativeto its full expansion capability. The SPB chamber 300A may be expandeddue to provision of lifting gas therein. In some embodiments, the SPBchamber 300A may be expanded to 10% or less, to 20% or less, to 30% orless, to 40% or less, to 50% or less, to 60% or less, to 70% or less, to80% or less, or to 90% or less of its full volumetric expansioncapability.

The SPB chamber 300B may be less expanded relative to the SPB chamber300A. For example, the chamber 300B may hold no lifting gas, or in someembodiments less lifting gas than the chamber 300A. The SPB chamber 300Ais located above the SPB chamber 300B. In some embodiments, the relativevertical positions of the SPB chamber 300A and 300B may be reversed,where the chamber 300B is on top.

After liftoff and expelling of the lifting gas, as described herein, theSPB's 300A, 300B may receive external ambient air and expel internallystored ambient air to add and remove ballast air, for example using thecompressor 356 or other compressors described herein, to controldownward forces on the system 112. The compressor may be located at ornear the lower end of the SPB 300B or included with the stratocraft 400and fluidly connected via a hose or tube, as described herein. Theambient air may be stored in and released from a continuous interiorvolume of the SPB's 300A, 300B, as described herein.

In some embodiments, the chambers 300A, 300B may have separatedcompartments therein and/or be separated from each other. In someembodiments, the chamber 300B may have a ballast air compartment withlittle or no ballast air prior to ascent and the chamber 300A may have alifting gas compartment with sufficient lifting gas to provide therequired free lift or ratio of free lift of the LTA system, asdescribed. In some embodiments, the SPB chamber 300A may be a liftinggas SPB, such that it only or primarily holds lifting gas. In someembodiments, the SPB chamber 300B may be a ballast air SPB, such that itonly or primarily holds ballast air. Therefore, modifications to theembodiments having a continuous interior volume within the chambers300A, 300B may be implemented.

FIGS. 24A-24C depict embodiments of various altitude control techniques.The LTA system 100 is shown having the ZPB 200, the SPB 300 and thestratocraft 400. The LTA system 100 may include any of the features ofother LTA systems as described herein. As shown, the LTA system 100includes the SPB 300 having the lifting gas valve 399 and the ballastair valve 398. The valves 398, 399 may be used as further described forvarious altitude control techniques.

As shown in FIG. 24A, the valve 399 may be opened to allow for liftinggas to vent out of the balloon 300 or a compartment thereof. The valve399 may allow for excess “free lift” gas to be vented after launch. Forexample, the lifting gas may be used to provide free lift to ensuresufficiently swift ascent and clearance of ground obstacles, asdescribed herein. After a desired altitude is achieved, any excesslifting gas may be vented out of the valve 399 using any of the controlmethods described herein. The lifting gas is shown exiting out of theballoon 300 from the valve 399 as an example flow path. The gas may ventin any number of flow paths from the balloon 300. The valve 399 may beclosed to achieve neutral buoyancy and maintain a constant altitude. Theballast air valve 398 may be open or closed to vent or not vent ballastair. The valve 398 may be closed to achieve neutral buoyancy andmaintain a constant altitude.

As shown in FIG. 24B, the LTA system 100 may be controlled to take inambient air as ballast to increase the mass of the LTA system 100.Increasing the mass of the LTA system 100 may cause it to descend if theresulting mass is greater than the mass of atmosphere displaced by theLTA system 100. As shown, the LTA system 100 is descending as indicatedby the arrow. The ambient air is being sucked into the compressor in thestratocraft 400 portion of the LTA system 100, flowing up through a hoseor tube, and into the balloon 300. The ambient air may flow into aballast air compartment of the SPB 300, as described herein. The air maybe pumped into the SPB 300 until the desired altitude and/or downwardvelocity is achieved.

As shown in FIG. 24C, the LTA system 100 may be controlled to emitballast air to decrease the mass of the LTA system 100. Decreasing themass of the LTA system 100 may cause it to ascend if the resulting massis less than the mass of atmosphere displaced by the LTA system 100. Asshown, the LTA system 100 is ascending as indicated by the arrow. Thestored air is flowing out from the valve 398. The valve 398 may beoperated as described herein. The stored air may flow out from a ballastair compartment, as described herein. In some embodiments, the ballastair may flow from the SPB 300, down through a tube or hose, and out ofthe stratorcraft 400 portion of the LTA system. The air may be ventedfrom the SPB 300 until the desired altitude and/or upward velocity isachieved.

The various embodiments of the LTA system 100 and features thereof maybe implemented in a number of approaches. Some example embodiments areprovided here. In some embodiments, a lighter-than-air (LTA) highaltitude balloon system in communication with a local or remote controlstation comprises a zero-pressure balloon (ZPB) configured to receivetherein a first LTA gas composition to provide an upward lifting forceto the balloon system; a super-pressure balloon (SPB) having an outerskin and configured to couple with the ZPB, the outer skin defining aninterior volume configured to receive therein a variable amount ofambient air from a surrounding atmosphere to provide a variable downwardforce to the balloon system, the SPB external to and suspended from theZPB. Optionally, a lighter-than-air (LTA) high altitude balloon systemalso comprises a centrifugal compressor configured to provide at least150 to 1,500 liters/second of the ambient air to the interior volume ofthe SPB at altitudes from about 50,000 feet to over 75,000 ft.

Optionally, a lighter-than-air (LTA) high altitude balloon system alsocomprises an adjustable valve configured to be adjusted to release thepumped-in ambient air from the interior volume of the SPB to thesurrounding atmosphere such that a resulting ascent rate of the balloonsystem is approximately 10,000 feet per hour at altitudes above about50,000 feet. Optionally, a lighter-than-air (LTA) high altitude balloonsystem also comprises two or more SPBs connected to the ZPB in somefashion. Optionally, a lighter-than-air (LTA) high altitude balloonsystem may also comprise a parafoil system releasably coupled with thepayload support and releasably coupled with an elongated ladder assemblyin a stowed configuration, the parafoil system configured to releasefrom the elongated ladder assembly and to deploy into a deployed flightconfiguration to controllably descend with the payload support to alanding site.

Optionally, a lighter-than-air (LTA) high altitude balloon system alsocomprises a solar array comprising one or more solar panels coupled withthe elongated ladder assembly or another location with access to thesun. Optionally, a lighter-than-air (LTA) high altitude balloon systemalso comprises one or more batteries and/or one or more fuel cellswherein the fuel cell(s) is configured to be powered by one or more LTAgases and/or a separate fuel supply and configured to recharge a batteryor provide power to equipment as may be required.

In some embodiments, a method of controlling a lighter-than-air (LTA)high altitude balloon system through a troposphere, tropopause andstratosphere is described. The balloon system comprises a zero-pressureballoon (ZPB) coupled with a super-pressure balloon (SPB), the SPBexternal to and suspended from the ZPB, a centrifugal compressor fluidlycoupled with the SPB and configured to pump ambient air into the SPB, anadjustable valve fluidly coupled with the SPB and configured to releasethe pumped-in ambient air from the SPB, a payload support coupled withthe SPB and configured to support a payload, an elongated ladderassembly coupling the payload support with the SPB such that the payloadsupport is located above or below the SPB when the balloon system is inflight, a solar array, and an air hose fluidly coupled with thecentrifugal compressor. The centrifugal compressor is fluidly coupledwith an interior volume of the SPB via the air hose.

The method may comprise determining a first range of latitude andlongitude coordinates corresponding to a first portion of the tropopausehaving a first plurality of altitudes corresponding respectively to afirst plurality of wind directions within the tropopause; controllablyreleasing, with the adjustable valve, the ambient air from the SPB toascend the balloon system from the determined first range of latitudeand longitude coordinates within the troposphere and through thetropopause to the stratosphere, wherein the balloon system travels alonga first variable trajectory through the tropopause due to the firstplurality of wind directions at the first plurality of altitudes withinthe tropopause, wherein the balloon system ascends at a plurality ofascent rates through the tropopause, and wherein at least one of theplurality of ascent rates is at least 10,000 feet per hour; determininga second range of latitude and longitude coordinates corresponding to asecond portion of the tropopause having a second plurality of altitudescorresponding respectively to a second plurality of wind directionswithin the tropopause; and controllably pumping, with the compressor,the ambient air into the SPB to descend the balloon system from thedetermined second range of latitude and longitude coordinates within thestratosphere and through the tropopause to the troposphere, wherein theballoon system travels along a second variable trajectory through thetropopause due to the second plurality of wind directions at the secondplurality of altitudes within the tropopause, and wherein the balloonsystem descends at a plurality of descent rates through the tropopause,and wherein at least one of the plurality of descent rates is at least10,000 feet per hour.

Optionally, a method of controlling a lighter-than-air (LTA) highaltitude balloon system also comprises traveling in a generallyhorizontal first direction through the troposphere to one of thecoordinates of the determined first range of latitude and longitudecoordinates before controllably releasing the pumped-in ambient air fromthe super pressure balloon to ascend the balloon system through thetropopause and into the stratosphere; and traveling in a generallyhorizontal second direction through the stratosphere to one of thecoordinates of the determined second range of latitude and longitudecoordinates after ascending to the stratosphere and before controllablypumping in the ambient air to descend the balloon system through thetropopause and into the troposphere, wherein the first direction isdifferent from the second direction. Optionally, a method of controllinga lighter-than-air (LTA) high altitude balloon system also comprisesmaintaining the balloon system within a persistence envelope comprisingportions of the troposphere, tropopause and stratosphere, whereinmaintaining the balloon system within the persistence envelope comprisescyclically repeating the following: traveling, from a starting positionwithin the troposphere corresponding to one of the coordinates of thesecond range of latitude and longitude coordinates, along the generallyhorizontal first direction through the troposphere to a first locationof the troposphere corresponding to one of the coordinates of the firstrange of latitude and longitude coordinates; ascending from the firstlocation of the troposphere through the tropopause along the firsthelical trajectory to a second location within the stratosphere;traveling along the generally horizontal second direction from thesecond location of the stratosphere to a third location of thestratosphere corresponding to one of the coordinates of the second rangeof latitude and longitude coordinates; and descending from the thirdlocation of the stratosphere through the tropopause along the secondvariable trajectory to an ending position within the tropospherecorresponding to one of the coordinates of the second range of latitudeand longitude coordinates.

In some embodiments a lighter-than-air (LTA) high altitude balloonsystem comprises a zero-pressure balloon (ZPB) configured to receivetherein an LTA gas to provide an upward lifting force to the balloonsystem; one or more super-pressure balloons (SPB) configured to couplewith the ZPB and configured to receive ambient air within an interiorvolume to provide a downward force to the balloon system, the SPB(s)external to and suspended from the ZPB; and a multi-stage centrifugalcompressor configured to pump the ambient air into the SPB to increasethe downward force to the balloon system, wherein the multi-stagecentrifugal compressor is configured to pump the ambient air into theSPB such that a resulting descent rate of the balloon system is up to orgreater than 10,000 feet per hour at altitudes above 50,000 feet; anadjustable valve configured to release the pumped-in ambient air fromthe SPB to decrease the downward force to the balloon system, whereinthe adjustable valve is configured to release the pumped-in ambient airfrom the SPB such that a resulting ascent rate of the balloon system isup to or greater than 10,000 feet per hour at altitudes above 50,000feet; a payload support coupled with the SPB and configured to support apayload; possibly with an elongated ladder assembly coupling the payloadsupport with the SPB such that the payload support is located above orbelow the SPB when the balloon system is in flight; a parafoil systemcoupled with the payload support and releasably coupled with theelongated ladder assembly in a stowed configuration, the parafoil systemconfigured to release from the elongated ladder assembly and to deployinto a deployed flight configuration to controllably descend with thepayload support to a landing site; and an air hose fluidly coupled withthe multi-stage centrifugal compressor, wherein the multi-stagecentrifugal compressor is fluidly coupled with the interior volume ofthe SPB via the air hose.

In some embodiments a lighter-than-air (LTA) variable high altitude airballast balloon system high altitude balloon system, hereafter LTAsystem, comprises a zero-pressure balloon (ZPB) configured to receivetherein an LTA gas composition to provide an upward lifting force to theballoon system; a super-pressure balloon (SPB) comprising an outer skinand configured to couple with the ZPB, the outer skin defining aninterior volume configured to receive therein a variable amount ofambient air from the surrounding atmosphere to provide a variabledownward force to the balloon system; and a control system comprising atleast one valve and at least one source of compressed air incommunication with the SPB; optionally an LTA system comprises asuper-pressure balloon (SPB) is configured to receive therein an LTA gascomposition to provide a supplemental upward lifting force to theballoon system; optionally an LTA system comprises a super-pressureballoon configured such that a portion of the LTA gas composition addedto the SPB to provide a supplemental upward lifting force can bereleased to the atmosphere at intervals determined by the controlsystem; optionally an LTA system comprises two or more SPBs connected inseries, external to and suspended from the ZPB; optionally, at least oneof the two or more super-pressure balloons is configured to receivetherein an LTA gas composition to provide a supplemental upward liftingforce to the balloon system; optionally, at least one of the two or moresuper-pressure balloons is configured such that a portion of the LTA gascomposition added to the SPB can be released to the atmosphere atintervals determined by the Control System; optionally the release ofLTA gas from the SPB and the amount of air in the SPB is controlled bythe control system; optionally an LTA system further comprises anelongated ladder assembly in a stowed configuration; a parafoil systemreleasably coupled with the elongated ladder assembly; a payload supportcoupled with the parafoil system and such that the parafoil system isconfigured to release from the elongated ladder assembly and to deployinto a deployed flight configuration to controllably descend with thepayload support to a landing site; optionally an LTA system furthercomprises a solar array comprising one or more solar panels coupled withthe elongated ladder assembly.

Q. Additional Considerations

The flow chart sequences are illustrative only. A person of skill in theart will understand that the steps, decisions, and processes embodied inthe flowcharts described herein may be performed in an order other thanthat described herein. Thus, the particular flowcharts and descriptionsare not intended to limit the associated processes to being performed inthe specific order described.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the spirit of theinvention. As will be recognized, the present invention may be embodiedwithin a form that does not provide all of the features and benefits setforth herein, as some features may be used or practiced separately fromothers. The scope of the invention is indicated by the appended claimsrather than by the foregoing description. All changes which come withinthe meaning and range of equivalency of the claims are to be embracedwithin their scope.

The foregoing description details certain embodiments of the systems,devices, and methods disclosed herein. It will be appreciated, however,that no matter how detailed the foregoing appears in text, the systems,devices, and methods may be practiced in many ways. As is also statedabove, it should be noted that the use of particular terminology whendescribing certain features or aspects of the invention should not betaken to imply that the terminology is being re-defined herein to berestricted to including any specific characteristics of the features oraspects of the technology with which that terminology is associated.

It will be appreciated by those skilled in the art that variousmodifications and changes may be made without departing from the scopeof the described technology. Such modifications and changes are intendedto fall within the scope of the embodiments. It will also be appreciatedby those of skill in the art that parts included in one embodiment areinterchangeable with other embodiments; one or more parts from adepicted embodiment may be included with other depicted embodiments inany combination. For example, any of the various components describedherein and/or depicted in the Figures may be combined, interchanged orexcluded from other embodiments.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art may translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

All references cited herein are incorporated herein by reference intheir entirety. To the extent publications and patents or patentapplications incorporated by reference contradict the disclosurecontained in the specification, the specification is intended tosupersede and/or take precedence over any such contradictory material.

The term “comprising” as used herein is synonymous with “including,”“containing,” or “characterized by,” and is inclusive or open-ended anddoes not exclude additional, unrecited elements or method steps.

All numbers expressing quantities of ingredients, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should be construed in light of the number ofsignificant digits and ordinary rounding approaches. For example, termssuch as about, approximately, substantially, and the like may representa percentage relative deviation, in various embodiments, of ±1%, ±5%,±10%, or ±20%.

The above description discloses several methods and materials of thepresent invention. This invention is susceptible to modifications in themethods and materials, as well as alterations in the fabrication methodsand equipment. Such modifications will become apparent to those skilledin the art from a consideration of this disclosure or practice of theinvention disclosed herein. Consequently, it is not intended that thisinvention be limited to the specific embodiments disclosed herein, butthat it cover all modifications and alternatives coming within the truescope and spirit of the invention as embodied in the attached claims.

1-6. (canceled)
 7. A high altitude balloon system comprising: acompressor; and a super pressure balloon comprising an interior volumeconfigured to house a lighter-than-air gas therein, to release thelighter-than-air gas to a surrounding atmosphere while the superpressure balloon is in flight, and to receive ambient air from thesurrounding atmosphere using the compressor while the super pressureballoon is in flight.
 8. The system of claim 7, wherein the superpressure balloon further comprises one or more valves in communicationwith the interior volume, wherein one or more of the one or more valvesis configured to open to release the lighter-than-air gas from theinterior volume to the surrounding atmosphere.
 9. The system of claim 8,wherein one or more of the one or more valves is configured to open torelease the ambient air from the interior volume to the surroundingatmosphere.
 10. The system of claim 7, wherein the super pressureballoon comprises: an upper chamber; and a lower chamber fluidlyconnected to the upper chamber.
 11. The system of claim 10, wherein theinterior volume is configured to receive lighter-than-air gas within thelower chamber and release the lighter-than air gas from the upperchamber.
 12. The system of claim 7, further comprising a control systemconfigured to control the release of the lighter-than-air gas from theinterior volume and the receipt of the ambient air into the interiorvolume.
 13. The system of claim 12, further comprising an environmentalsensor, wherein the control system is configured to control the releaseof lighter-than-air gas from the interior volume and the receipt ofambient air into the interior volume based on data from theenvironmental sensor.
 14. The system of claim 13, wherein the controlsystem is configured to control the compressor to provide ambient air tothe interior volume based on the data from the environmental sensor. 15.The system of claim 13, wherein the control system is configured tocontrol one or more valves to release the lighter-than-air gas and theambient air from the interior volume to the surrounding atmosphere basedon the environmental data.
 16. The system of claim 7, further comprisinga payload support coupled with the super pressure balloon by anelongated connector.
 17. The system of claim 7, further comprising afill tube fluidly connecting the compressor to the interior volume. 18.The system of claim 7, further comprising a zero-pressure balloonconfigured to receive a second lighter-than-air gas.
 19. The system ofclaim 7, further comprising a payload and a parafoil, wherein theparafoil is configured to separate from the balloon system to descendthe payload to ground.
 20. A super pressure balloon comprising: anenvelope defining one or more interior volumes, wherein one or more ofthe one or more interior volumes is configured to house alighter-than-air gas, wherein one or more of the one or more interiorvolumes is configured to release the lighter-than-air gas to asurrounding atmosphere while the super pressure balloon is in flight,and wherein one or more of the one or more interior volumes isconfigured to receive ambient air from the surrounding atmosphere whilethe super pressure balloon is in flight.
 21. The super pressure balloonof claim 20, further comprising a valve in communication with one ormore of the one or more interior volumes, the valve configured to opento release the lighter-than-air gas to the surrounding atmosphere. 22.The super pressure balloon of claim 21, wherein the valve is configuredto open to release the ambient air to the surrounding atmosphere. 23.The super pressure balloon of claim 21, further comprising a secondvalve configured to open to release ambient air to the surroundingatmosphere.
 24. The super pressure balloon of claim 20, wherein the oneor more interior volumes comprise: an upper chamber; and a lower chamberfluidly connected to the upper chamber.
 25. The super pressure balloonof claim 24, wherein the lower chamber is configured to receive thelighter-than-air gas and the upper chamber is configured to release thelighter-than air gas to the surrounding atmosphere.
 26. The superpressure balloon of claim 20, further comprising a payload and aparafoil, wherein the parafoil is configured to separate from the superpressure balloon to descend the payload to ground.